Kayla came to Salem in 1982, and was the third youngest of the Brady siblings, Roman, Kim, and Bo. She was involved briefly with David Banning, but, after he broke up with her, she began seeing Chris Kositchek. Kayla would eventually lose her virginity to Chris, but when he wouldn’t commit to future together, she left town.
In 1986, Kayla returned and set up a clinic on the Riverfront, where she met and fell in love with Steve Johnson. Kayla also befriended Adrienne Johnson, and the two roomed together. Steve was troubled by Adrienne, and had troubling memories about her. Steve began having nightmares, and turned away from Kayla.
In 1987, Kayla hid Steve when he was setup by Victor Kiriakis' henchman while trying to help Harper Deveraux. Later, Harper hired Kayla to be his son Jack’s nurse. Despite battling Hodgkin’s disease, Jack fell in love with Kayla, and the two eventually married because Steve continued to reject Kayla (he saw how happy Kayla made Jack, whom they believed was dying).
Kayla married Jack on September 15, 1987. Soon after she was poisoned by Harper Deveraux, who thought she had discovered that Jack was adopted. Kayla was taken from the Deveraux house by Steve, and when she awoke she refused to believe anyone was poisoning her. Kayla ran away, and was found passed out on the pier by Melissa Jannings, who became the prime suspect in her attempted murder.
When Kayla recovered, she and Steve began to have an affair, and when they were exposed in the papers, Jack was humiliated. Enraged over her betrayal, Jack raped Kayla and had Steve beaten up. Steve and Jack faced off on a rooftop and Jack fell off. Jack was rushed to the hospital but required a kidney transplant. His best chance for a successful match was his brother, and Steve agreed to donate the kidney because their mother Jo asked him to. Kayla filed for divorce and charged Jack with rape, but Jack's connections managed to get him off. Soon afterwards Kayla went back to work the Riverfront Emergency Clinic she started in 1986.
Later that year Kayla was attacked by the Riverfront Knifer. During the attack an explosion caused her to lose her hearing and speech, and she blacked out the face of her attacker. When she finally recalled who attacked her, she went to Kimberly to reveal that Harper was the Riverfront Knifer. Unfortunately Harper took Kim and Kayla hostage, but they were eventually saved by Steve and Shane Donovan. After Kayla was safe she underwent surgery to repair her hearing. The surgery was a success, but it couldn't restore her speech. Steve proposed to Kayla, and she accepted. On July 28, 1988 Kayla and Steve wed, and Kayla said "I do" her speech had returned. Steve and Kayla honeymooned in the Orient where they came upon a little deaf boy named Benjy. Benjy was all alone and when his mom couldn't be found they took him in.
Steve and Kayla brought Benjy back to Salem and they even considered adopting Benjy but his mother Ellen showed up. Ellen confessed to them that Benjy's father was a dangerous man, but to protect him she let them take care of him. A short time after their talk, Ellen was found dead on the pier. Eventually it came out that Benjy was the son of Stefano DiMera. Benjy's grandfather Orion eventually picked Benjy up and took him where they could live in safety.
Later in 1988 Jack helped Victor Kiriakis stage a jail break for Harper. Jack was promised a share of Harper's money just as soon as Harper was out of the country. The plan failed, and Harper was shot trying to get to the airport. When Jack took him to the Riverfront Clinic, Harper took Kayla hostage again. Steve managed to save Kayla, and Harper went back to prison.
In 1989, Steve found a badly burnt Nick and agreed to hide him and keep his secret. Steve eventually had to tell Kayla about Nick. After Nick was strong enough he left Steve and Kayla's care and relocated to an old mansion he owned. Unfortunately, the mansion only brought bad luck to Nick. An old acquaintance named Eddie was holding Eve hostage there and was looking for some old money of Harper's that Nick had hidden there. Steve and Kayla helped Nick try to lure Eddie into a trap but where accused of conspiring to hide stolen money. Eventually, Eddie was shot and killed and, as a thank you, Nick gave the old mansion to Steve and Kayla.
Just when Steve and Kayla soon learned they were expecting, and just when they thought their life had returned to normal, Marina Toscano-Johnson showed up, claiming to be Steve's wife. Steve was indeed married to her, and believed he had killed her when they got into an argument on a ship and she fell overboard. Marina didn't want Steve back, she just wanted his help in retrieving an old key they had thrown into the sea long ago. Kayla encouraged Steve to help her in hopes she would grant him a divorce, and they all traveled to Italy to retrieve the key. After it was found Steve got into a fight with some of Victor Kiriakis' men, and his glass eye and socket was damaged beyond repair, forcing him to wear his patch again. Back in Salem, Kayla confronted Marina for the danger she had put her family in, and they argued in her hotel room. Kayla pushed Marina down and left her very much alive. Unfortunately Kayla was kidnapped by Victor Kiriakis who wanted the real key Marina had hidden in Steve and Kayla's house.
When Isabella handed over the real key to Victor, Kayla was safely returned to Steve. Kayla was very pregnant at the time, and she and Steve wanted to remarry before the baby's birth. Unfortunately Kayla was arrested during the wedding for the Marina’s murder. Victor had sent Roman (John Black) and Abe Carver a tape on which Kayla threatened to kill Marina then pushed her down and left the room. The tape had been doctored, but Roman was forced to arrest Kayla. Kayla stood trial for the murder and was eventually found guilty.
Convicted of murder, Kayla was sent to prison. Shortly afterwards, she gave birth to her daughter Stephanie on February 19, 1990 and she allowed Steve to raise the baby. Steve hired a woman named Kelly Parker as the baby’s nanny. Unknown to Steve, Kelly was actually a deranged woman named Sheila Salsbury who had lost her baby in birth at the time that Kayla had hers. Sheila, who had become obsessed with the baby, kidnapped Stephanie.
Kayla escaped from prison to search for her and, with Steve, fled the country. They followed Sheila to Australia, where they met up with Bo and Hope. With their help, Kayla and Steve managed to recover their child. When they had learned that Kayla was exonerated of Marina's death, everyone decided to return to Salem.
In 1990, Harper escaped from prison and vowed to have his revenge on Steve. At Steve and Kayla's second wedding, Harper planned to execute Steve from the church bell tower. However, Jack learned of Harper's plan and stopped him by pushing him to his death from the top of the tower. The wedding went on as planned and Steve and Kayla were legally married on August 13, 1990.
After they were wed, Steve decided to change his life and become a police officer. While patrolling the harbor late one night, Steve spotted a suspicious looking boat. When he investigated it he found a card that was addressed to Bo from Lawrence Alamain. Suddenly the boat exploded. Steve was knocked into a coma, but eventually came around. But, because he was a threat to Lawrence, Lawrence had his IV poisoned and Steve died. Before his coffin was buried it was switched with an empty casket.
A grief stricken Kayla moved in with Shane so he could protect her from Lawrence. Shane vowed to find her husband's killer. The two worked together and all the fingers pointed at one person, Lawrence. Throughout their investigation, the two fell in love, but problems arose when Kimberly returned to Salem in 1991 and was not happy to see her sister and ex-husband growing so close.
At a museum party in 1992, Shane's attempt to disarm a bomb planted by the Torres failed and he was left paralyzed. Shane refused to have surgery that could restore the use of his legs. Shane put up a wall that only Kayla could knock down. She helped him recover and the two realized that they had fallen in love. Shane eventually regained the use of his legs, but the tension between Kim and Kayla put a strain on his relationship with Kayla. Eventually, Kayla moved to Los Angeles to work in a clinic and Shane returned to England.
Over the next fourteen years, Kayla would raise Stephanie as a single parent and also attend medical school to become a doctor. However, she never stopped loving Steve and continued to mourn his passing. Kayla would also return to Salem several times, however the character always remained off-screen.
Kayla officially returned to Salem in 2006 to celebrate her bother Frankie’s marriage to Jennifer Horton. However, she was utterly shocked when a very-much-alive, although amnesic, Steve appeared at the church. At first he didn't recognize her, and she was devastated to think that he didn't know who she was, but within a few months his memory returned. Although the two had some close calls, including Kayla being poisoned, they began trying to rebuild their life together, and everything seemed to be going better when Steve finally regained his full memory of their life together.
To celebrate Steve’s memory returning, the happy couple took a trip and, when they returned, they became foster parents to a little boy they nicknamed Pocket because of his tiny stature. In realty, “Pocket” was Tyler Kiriakis, Philip Kiriakis’ son via a surrogate. Eventually, Philip decided it was best to give Tyler up for adoption and Kayla and Steve were forced to hand over the child to the adoptive parents, Mr. and Mrs. Wilkens. However, this prompted Kayla and Steve to want another baby. Although Kayla had some difficulties conceiving because of her age, she and Steve eventually did. Unfortunately, it would end up a bittersweet time as they had found out Stephanie had been raped. Kayla and Steve rallied around their daughter as she recovered.
However, a woman from Steve’s past soon surfaced to further complicate their lives. During a trip to Ireland in early 2008, Kayla and Steve came in contact with Ava Vitali - the daughter of mob boss, Martino Vitali. He had dated Ava while suffering from amnesia and, when they broke up, Ava suffered a mental breakdown. Afterwards, her father kept her on medication and locked up. But, when Ava escaped she plotted to kidnap Kayla and get Steve back. However, Ava mistakenly kidnapped Hope believing she was Kayla. Steve, Kayla, and Bo soon followed to rescue Hope, but soon found themselves captives as well. While being held, Kayla discovered that the pills that Ava had been taking kept her from ever becoming well. Once everyone was freed, Kayla put Ava into a treatment program and Ava made a full recovery. Grateful, Ava left Kayla and Steve alone.
Although freed from the Vitali compound, the stress from the hostage situation caused Kayla to go into premature labor. She delivered a baby boy at 26 weeks. Baby Joey was hospitalized for the first few weeks of his life, but he soon recovered and was sent home with Steve and Kayla. Over the next few months, Kayla concentrated on her family and her new job as Chief of Staff at University Hospital.
In February of 2009, Kayla was once again involved in a hostage situation, this time at the hospital. During the struggle, Hope accidentally shot Kayla when perpetrator moved out of the way. Kayla immediately went into surgery to remove the bullet. Kayla made a full recovery and forgave Hope.
Shortly after her ordeal, Kayla decided to leave University Hospital in order to run a free clinic in a third world country. With Steve and Joey in tow, Kayla once again left Salem.
Kayla returned to Salem in the fall of 2011 without Steve. Within a few months, Kayla revealed that she and Steve had been arguing for months. She said that he missed his life of adventure, so he contacted Shane and rejoined the ISA. Kayla and Steve filed for divorce in 2012.
Kayla spent her time helping out Caroline at the Brady Pub. She was also part of the support system for Abe after Lexie died. When Kayla and Steve decided to end their marriage, Abe offered Kayla support as well. The two became very good friends.
After Lexie's death, Kayla took over as chief-of-staff at Salem U hospital.