Morasca is originally from Western Pennsylvania. She is an only child. Before appearing on Survivor, Morasca was a college student at the University of Pittsburgh and worked as a swimsuit model.

Originally part of the all-female Jaburu tribe, she almost immediately bonded with fellow contestant Heidi Strobel, which led to a long-standing alliance. Together with Shawna Mitchell and Deena Bennett, the alliance voted out Janet Koth and Joanna Ward. After the tribal switch in episode 5, Jenna created further allies with Alex Bell and Rob Cesternino, but at the price of former alliance member Shawna.

During one immunity challenge, Jenna and Heidi stripped off their clothes for peanut butter and chocolate. After making the merge, Jenna was relatively safe at the start as the majority of the tribe chose to vote off outcasts Roger Sexton and Dave Johnson. At the final 8, the new alliance of Jenna, Heidi, Alex and Rob targeted Deena, and she was voted out. At the final 7, Rob betrayed his alliance and blindsided Alex. At the Final 6, Jenna and Heidi scrambled to stay in the game, trying to break up the now-alliance of Rob, Matthew Von Ertfelda and Butch Lockley. When Christy Smith would not commit to either side, Rob approached the girls with an offer to get rid of Christy (deemed the "loose cannon"). Because it meant that the targets were off their own backs, both Jenna and Heidi accepted and Christy was voted off. At the Final 5, Jenna and Heidi found themselves on the outside once again. The men targeted Heidi, believing her to be physically stronger than the sick Jenna, and she was voted out.

At the Final 4, Jenna found herself facing an uphill battle against the three-man alliance. Jenna, however, managed to win immunity, securing her place in the Final 3. Jenna sided with Rob and Matthew to vote out likable (and hence threatening) Butch. At the Final 3, Matthew approached Jenna for a possible final 2 alliance to which Jenna agreed. At the immunity challenge, Matthew immediately stepped down, knowing both Jenna and Rob would take him to the final 2. Sensing he was in trouble, Rob tried to strike a deal with Jenna, but she did not budge. Jenna went on to win immunity and voted off Rob. In the end, Jenna beat Matthew in a 6–1 vote to become the Sole Survivor. Matthew's behavior, deemed as "weird", together with his lack of social connections and interactions, helped Jenna win the votes of Dave, Deena, Alex, Heidi, Rob, and most surprisingly Christy, who when voted off, claimed she would never vote for Jenna or Heidi to win the million dollars. Matthew received his sole vote from Butch. With her win, Morasca was the youngest contestant to ever win Survivor.

In 2004, Jenna was invited back to play once more on Survivor: All-Stars. As part of the Mogo Mogo tribe, Jenna and her tribe won immunity in the first two episodes. However, in episode three, Jenna decided to quit the game, regretting leaving her dying mother, who had been in a battle with cancer for 12 years. She withdrew from the game to go home. Her mother died eight days after Jenna returned home.

In 2005, Morasca replaced Richard Hatch as co-host (with Dalton Ross) of CBS's Survivor Live, an internet talk show devoted to the current season of Survivor. She has since hosted the show throughout five entire seasons - Survivor: Palau, Survivor: Guatemala, Survivor: Panama, Survivor: Cook Islands and Survivor: Fiji.

Morasca's strip with fellow contestant Heidi Strobel led to a spread in Playboy magazine, which reportedly earned her yet another million dollars. She also appeared near-nude in an anti-fur ad for PETA with her boyfriend, Survivor: Africa winner Ethan Zohn that featured the slogan "We'd Rather Go Naked Than Wear Fur!" In addition, Morasca modeled swimwear and was the CEO of a model scouting company called Model Challenge USA, which she founded in 2004.

In 2003, Morasca had a part in the Off Broadway play Pieces. Morasca also had a minor role in the made-for-TV movie The Scorned in 2005. She was also a contestant on a the February 28, 2005 episode of Fear Factor, which starred former reality television contestants. She was eliminated in the second round by Omarosa Manigault-Stallworth. Morasca appeared on the premiere episode of Celebrity Paranormal Project on VH-1, along with Gary Busey and several others. Morasca and Ethan Zohn stars also in Drive-In Horror and appeared also as guest sous chefs on the Food Network show Dinner: Impossible.

On the March 12 edition of Total Nonstop Action Wrestling's Impact! program, Morasca made her debut in a backstage interview with Mick Foley. She then appeared in backstage segments with Kevin Nash and his alliance The Main Event Mafia. It was later revealed by Kurt Angle that Morasca was the financial backer to the Mafia, and the money she provided was used to lure Samoa Joe to the stable. Morasca was regularly seen bickering with fellow Mafia valet Sharmell, leading to a catfight backstage on the May 28 edition of Impact!. On the July 9 edition of Impact it was revealed that Morasca had hired Awesome Kong to train her for her upcoming match against Sharmell at Victory Road. Morasca won her in-ring debut against Sharmell at Victory Road after Kong knocked Sharmell out. After the match, Morasca slapped Kong, who then slammed her down to the mat and splashed her.

In 2004, Morasca was on the Board of Directors for Animal Friends in Pittsburgh.