Poppy makes her first appearance in The Serena Also Rises, as a socialite whom Serena van der Woodsen befriends. The two hang out a lot, and are invited to sit front row at Eleanor Waldorf's Fashion Week Show. Serena, who is worried about her friendship with Blair Waldorf, doesn't think going is a good idea, since she always watches Eleanor's fashion show with Blair. Poppy suggests they invite Blair to the Marc Jacob's after party they were invited do, and Serena agrees to ask. When she does so, Blair turns her down and is angry that Serena is blowing off their tradition. At the show, she has Serena's seat moved to the back but Eleanor has it moved back up front with Poppy. When Blair tries to sabotage Jenny Humphrey by having all the models sent home, Serena and Poppy step in to model the clothes. Before she goes out to walk, Serena admits to Poppy that she's concerned about hurting Blair's feelings. Poppy convinces her that she shouldn't be afraid to shine and forget what Blair thinks. Serena decides to model, and the two leave together followed by the paparazzi.
After this, Serena and Poppy don't see each other much until the run into one another in Remains of the J. Serena explains how she got back together with Dan Humphrey but broke up again, and she's still friends with Blair. Meanwhile, she and Lily van der Woodsen are planning a Sweet Sixteen party for Jenny, that she gently declines. After being asked by Hazel Williams if she cancelled the party because of Penelope Shafai's party, Serena calls Poppy to asks for her help. They take Jenny shopping to buy her a dress, and then plan an even larger party than before. However when Jenny discovers what Serena did, she sabotages the party by sending out a Gossip Girl blast about it. After things get out of control, Poppy leaves, and eventually Serena catches up with her. They have a drink together, and Poppy admits she thinks Serena's life is stuck in a rut. She invites her to come to Spain with her and her boyfriend, Gabriel Edwards, and Serena decides to go.
Soon after, Serena returns to New York but Chuck Bass is suspicious, since he saw Poppy before she returned. It's revealed that Serena believes that she married Gabriel after they hooked up, although she finds out it didn't really happen. They enter into a relationship in Seder Anything. After dating briefly, Serena admits to Blair that Gabriel is hard to make plans with and he just disappears during dates. Blair takes it upon herself to find where he's going. Along with Chuck, the two discover that Gabriel is seeing Poppy on the side. She tries to tell Serena, who tells her to stay out of it so she can figure it out for herself. She asks Gabriel what the truth is, and he says that he's trying to start up a company to bring internet to kids abroad. He explains that Poppy has all his business contacts and his investors and if he leaves her forever, she'll pull out and he'll lose everything. Serena decides to give him a week to finish all the contracts. At a party later, Chuck and Blair bring Poppy and Gabriel together to corner them. They have a huge fight which ends with Gabriel ending things with Poppy and him losing her contacts. Afterwards, Serena tells him to use the people at her mom's party to invest, and he is able to pull hundreds of thousands in new investments. He also gets Rufus Humphrey to invest Dan Humphrey's college money. However, it's revealed that he and Poppy staged the fight and are working together to con people (Southern Gentlemen Prefer Blondes).
When Serena finds out, she tries and fails to get Gabriel to give the money back. He tells her that Poppy is the puppet master and the only one to able to get the money back. Serena, Nate, Chuck, Blair, and newly arrived back Georgina Sparks plot to get the money back. Meanwhile, Dan finds out that his college money was lost in the ponzi scheme and informs Lily van der Woodsen, who decides to pay everyone back herself. She tells Serena to leave it alone, and even has Poppy over for tea. Poppy reveals she's headed to Miami to stay with her cousin after the Gabriel thing, and Serena tries to tell Lily to call the police. After Lily lets her leave, Serena begins a new plan. The gang dress Georgina up as a naive Christian girl, who is looking for a philanthropic opportunity. They set her up with Poppy, who uses the internet plan as her charity. Georgina hands over a bundle of money, but the police set up to catch Poppy end up arresting Serena for theft of her family bracelet. As a result, Poppy gets away. However, Georgina eventually transforms back into her old self and decides to take Poppy down herself since the original plan failed (The Wrath of Con). In the season finale The Goodbye Gossip Girl, Georgina tells Dan she got all the money back, including his college money.
In Rufus Getting Married, Georgina reveals she had Poppy deported.
In High Infidelity, Poppy reappears as another designer being photographed with Blair for Women's Wear Daily. Thinking she was set up by Nelly Yuki, Blair sends her minions to investigate Poppy's collection and learns she used the same fabric. She decides to sabotage the line, but eventually discovers that their was no malice intended; they just happened to like the same fabric. Afterwards, Nelly decides to give Poppy all the magazine space and kick Blair's section out.