The Biggest Loser (season 2) is the second season of the NBC competitive reality television series entitled The Biggest Loser. The second season premiered on September 13, 2005, and like season one features overweight contestants who compete by trying to lose the most weight. The show is hosted by comedian Caroline Rhea, with Bob Harper and Jillian Michaels joining as the two personal trainers.

The contestants were divided into two teams: men in red and women in blue, with each team assigned to their own personal trainer of the opposite sex. Each week, the team which had the lowest percentage of total weight-loss was required to vote out one member of their own team.

The show concluded November 29, 2005, when Matt was declared "The Biggest Loser", winning $250,000. Seth was awarded $50,000 for his second place finish, and Suzy was awarded $25,000 for third. Of the non-finalists, Pete had lost the highest percentage of weight and received the $100,000 prize.