The main event of the WSOP has been the $10,000 buys-in no-limit Texas Hold 'Em tournament since 1972. (In 1971, the buy-in was $5,000.) Winners of the event not only get the largest prize of the tournament and a gold bracelet, but additionally their picture is placed into the Gallery of Champions at Binion's.

The winner of the Main Event has traditionally been given the unofficial title of World Champion. However the game's top professionals have stated that the recently-added $50,000 H.O.R.S.E. event is the one which ultimately decides the world's best player. H.O.R.S.E. is an event in which Hold 'em, Omaha, Razz, Seven Card Stud and Eight-or-better are all played. The H.O.R.S.E. tournament was won by Chip Reese in 2006 and Freddy Deeb in 2007. It should be noted that the professionals played a major role in convincing WSOP management to stage an event with a much larger buy-in than the Main Event; the growth of poker tournaments and the World Series (by way of "The Moneymaker Effect") had resulted in fields with a far greater number of amateurs in proportion to professionals. Hence, the Main Event now has a much greater likelihood of producing winners who are amateurs and/or relatively unknown players. The professionals sought to create an event which was far more likely to produce a more well-rounded poker professional as the eventual winner. The $50,000 buy-in, being five times larger than the buy-in for the Main Event, has thus far tended to deter amateurs from playing in the H.O.R.S.E. tournament.

The Gallery of Champions in 1979There have been many memorable moments during the main events, including Jack Straus's 1982 comeback win after discovering he had one $500 chip left when he thought he was out of the tournament.

Four players have won the main event multiple times: Johnny Moss (1971 and 1974), Doyle Brunson (1976 and 1977), Stu Ungar (1980, 1981 and 1997) and Johnny Chan (1987 and 1988).

The end of the 1988 main event was featured in the movie Rounder’s. Chris Moneymaker and Greg Raymer, the winners in 2003 and 2004 both qualified for the main event through satellite tournaments at the PokerStars online cardroom.   Jerry Yang, the winner in 2007, had only been playing poker for two years prior to his victory. He won his seat at a $225 satellite tournament at Pechanga Resort & Casino.

With the exception of winners of the World Series of Poker Main Event satellite tournaments (who automatically win a spot in the main event), all remaining players (including former champions, celebrities, and professional poker players) must supply the $10,000 buy-in in order to participate.