Chelsea was introduced as Abby's best friend, supposedly a 'good girl', but in reality Chelsea was encouraging Abby to smoke, drink, and lie to her mother. After meeting Abby's family friend Patrick Lockhart, Chelsea became obsessed with Patrick and determined to have him, enlisting Abby's help in first keeping Patrick away from Jennifer Deveraux, and later also enlisted Abby to help her keep Billie and Patrick apart. Chelsea was so determined to get Patrick for herself she drugged Patrick, and when that didn't seem to work, she spiked Billie Reed's drink at Alice's, not realizing it would drive Patrick and Billie into each other's arms. On the day of Abby Deveraux's seventeenth birthday, Chelsea, Abby and her parents had been out for the day until they ended up in a horrific car accident which took the life of both of Chelsea's parents. Chelsea was left on her own until Billie Reed stepped up and agreed to assume responsibility for Chelsea, and the two ended up moving in with Patrick Lockhart, much to Chelsea's delight.
Not long after moving in (and a number of close encounters with Max Brady), Chelsea was horrified to learn that the people who had raised her, the Bensons, were not her parents at all -- Bo and Billie were! Years earlier, Billie and Bo had believed their daughter, Georgia, had been stillborn, but she had been stolen by the DiMeras. She hated Billie with a passion because she considered Billie her prime competition to get Patrick, and she believed Billie had dumped her without a second glance. Chelsea also had a problem with driving, and after two close calls had her license revoked. At Bo's insistence she began taking driving lessons, and after she assured him that her instructor thought she was doing great, Bo agreed to lend her his car on New Year's Eve. Unfortunately, Chelsea took her attention off the road for a moment, and hit something. Hours later she realized it was her younger half-brother Zack, who died as a result. Chelsea was terrified that Bo would turn her in, but Billie stepped up to take the blame. Bo found out that Chelsea has been driving the car and tried to protect her, but Hope was furious with Chelsea. Chelsea schemed to keep Bo and Hope apart so that Hope would not convince her Bo to turn Chelsea in for Zach's accident. Eventually, Chelsea did turn herself in for being responsible for the accident and she was given community service for her involvement in Zach's death.
While working her community service at the hospital, she came across paper work that said that Shawn Douglas was Claire's biological father, not Phillip. Chelsea knew that Shawn would not believe her, so she left the paperwork for Shawn and Belle to find. When they found it, they thought it was a joke. A fingerprint sample revealed that Chelsea's prints were all over the paper. Chelsea was arrested. Bo convinced Shawn and Claire to have a DNA test. The test proved that Shawn was Claire's dad and all charges were dropped against Chelsea.
Abby introduced her geeky cousin, Nick Fallon, to Chelsea one night at Dune. Nick immediately became fascinated with Chelsea, but Chelsea did not return those feelings. Determined to find a boyfriend, Chelsea, using the screen name "Dark Angel", began corresponding online with someone named "Lonely Splicer". "Lonely Splicer" turned out to be Nick. When Chelsea found out that Nick was "Lonely Splicer" she was so upset that she did not even want to be friends with Nick. Upset over loosing Chelsea's friendship, Nick slept with Chelsea's mother, Billie.
To win favor back with Bo and Hope, Chelsea volunteered to take money to Belle, Shawn, and Claire who were hiding in Canada. Bo insisted that Nick go with Chelsea. On the trip, Nick and Chelsea's relationship turned flirtatious. Not long after they returned, Chelsea and Nick began dating. Chelsea found out that Nick had a one night stand with Billie. Eventually, Chelsea forgave Nick and the two continued dating. Chelsea mended her relationship with Bo and Hope and moved into their house.
In the summer of 2007, Stephanie returned to Salem and convinced Chelsea to work with her as a waitress for "Touch the Sky" airlines- jet service to Las Vegas that serviced high rollers. Chelsea formed a flirtatious relationship with Jett Carver, one of the pilots on the plane, despite the status of her relationship with Nick. Unfortunately, the owner of the business, Jeremy Horton, was also smuggling knock-off designer clothes for a gentleman who was working for the DiMeras. Chelsea witnessed Jett Carver, who was working undercover ISA, get shot in the back. Chelsea was conflicted over her feelings for Jett, but eventually returned back to Nick.
At the end of the summer, Chelsea and Stephanie went back to college and decided to pledge a sorority. They became active in Alpha Chi Theta. One by one, Chelsea's sorority sisters reported that they had been drugged and raped by Ford Decker. Chelsea, Billie, and some of the other sorority sisters tried to take the information to the dean, but Ford Decker's dad was very good friends with the dean and no action was taken against Ford. Chelsea and her sorority sisters decided to teach Ford a lesson. They lured him to the sorority house where Chelsea drugged Ford's drink. The intent was to embarrass Ford, but the night turned violent when Ford drugged Chelsea's drink and tried to rape her. When a drugged Chelsea tried to run upstairs, a drugged Ford fell down the stairs while chasing her. Ford died from the fall. The sorority sisters decided to hide the body. Chelsea kept the secret for weeks until finally telling Ford's dad and the police what happened to Ford. Ford's dad threatened to press charges against Chelsea, but Victor stepped in and convinced Ford's dad to let the issue go.
In the spring of 2008, Bo fell sick with a pancreas disease and needed a donor. Chelsea was a match. She donated part of her pancreas to her dad and in the process, suffered an infection during her recovery from the transplant. Due to internal scarring in her abdomen, she will not be able to have children. Chelsea starts to grasp the gravity of her infertility during the birth of her cousin, Joey. But, the transplant did leave her with something else. Chelsea fell for the Dr. Daniel Jonas, who performed the transplant. Chelsea realized her feelings for Daniel and officially ended her relationship with Nick to pursue a relationship with Daniel.
Chelsea and Daniel fought their attraction for a while. He had a rocky romantic history and she was quite a bit younger than him. But, the two eventually gave into their mutual attraction and began publicly dating in July of 2008. Their happiness was short lived when Chelsea found out that while she was hospitalized during the transplant, Daniel had slept with Kate Roberts, Chelsea's grandmother. Chelsea wanted nothing to do with Kate or Daniel. She left the country to help Max, Stephanie, and Nick find Max's sister.
When Chelsea returned from France, she learned that Kate was sick. Kate had lung cancer. Despite the fact that Kate and Daniel were openly dating, Chelsea forgave Kate and helped her through her cancer. Chelsea turned to Max Brady for support. The two grew closer and after getting Stephanie's blessing, began dating again.
In the spring of 2009, Chelsea learned that her mother, Billie, was in a very serious car accident. Her condition would require multiple surgeries and intensive therapy. Chelsea moved to London to help her mother through the recovery. Max soon joined her in London.