The recent University of Southern California graduate is a top contender in the 400 individual medley, will be aiming to surprise in the 200 IM and is also a formidable challenger in the 200 butterfly.
Hungary has a long history of success in the individual medley, with Tamas Darnyi sweeping all four IM golds at the 1988 Seoul and 1992 Barcelona Games. Attila Czene won the 200 IM at Atlanta in 1996, while on the women's side Krisztina Egerszegi won five IM golds between 1988 and 1996.
More recently, Laszlo Cseh took silver in both the 200 and 400 IM behind Michael Phelps at the 2008 Beijing Games.
"We train pretty hard and we're pretty tough. For IM swimming, especially the 400, you have to train hard and you have to have really good endurance," Hosszu told The Associated Press. "We see the example of how they (others) do in the IM's, so we want to follow."
Hosszu has never lacked motivation for long training sessions — in fact her last name translates as "long." But when she arrived at USC following a frustrating Beijing Olympics in 2008, she didn't have much else to offer.
"The way she was training before she got to USC was just grind out the yardage, not a lot of technique," said her coach at USC, Dave Salo, who she continues to train under. "When she got out and started swimming with us, it was like, 'Whoa, this is very different, very enlightening. Coaches are really giving me a lot of instructional technique work that I need to work on.'"
Having failed to crack the top 10 in any of her events in Beijing, Hosszu was ready to listen.
"She's just a very great trainer," Salo said. "She'll do anything, works harder than anybody."
Her improvement became evident when Hosszu won the 400 IM at the 2009 world championships in Rome, plus bronze in the 200 IM and the 200 fly. She was then named Hungary's 2009 female athlete of the year.
But despite coming off a collegiate season featuring three NCAA titles, Hosszu came away without any medals from the 2011 worlds in Shanghai.
"She had a great NCAA last year and got distracted by family coming over and had a terrible world championships," Salo said. "She came back more committed and more dialed in than she's ever been."
Hosszu's return to form was evident at this year's European Championships in front of her home fans in Debrecen, Hungary, when she won three golds.
Still, Hosszu isn't the outright favourite for any of her events in London, where she'll have to contend with the likes of Elizabeth Beisel, the American who holds the fastest time in the 400 IM this year; Stephanie Rice, the Australian who swept both IM's in Beijing; local favourite Hannah Miley of Britain; and Mireia Belmonte Garcia of Spain.
Hosszu thinks her best shot at gold is in the 400 IM.
"For me, the 200 is a little (tougher)," Hosszu said. "It's harder for me to get out and sprint."
The 400 IM is on the opening day of pool competition Saturday, then three days later Hosszu will have 200 fly heats and semifinals on the same day as the 200 IM final.
At Salo's Trojan Swim Club, Hosszu trains with the likes of breaststroke standouts Rebecca Soni and Jessica Hardy, plus Kosuke Kitajima, Eric Shanteau, Ricky Berens and Markus Rogan.
"I don't have to try to motivate myself," Hosszu said. "I just look at one side and there's an Olympic champion and the other side a world record-holder."
The presence of Soni and Hardy are particularly helpful, since breaststroke is Hosszu's worst stroke.
"Sometimes I go over for training with the breaststroke group and try to work on technique," Hosszu said. "That helps a lot."
Having grown up in Bafa, a small town in southern Hungary, Hosszu didn't speak much English before she moved to California. Now, she has a decidedly Californian accent. She graduated from USC with a psychology degree and is considering starting graduate school in a year or two.
For now, however, medals are the only thing on her mind.
AP Sports Writer Beth Harris contributed to this report.