Jaan Ehlvest (born 14 October 1962) is a chess player, who was awarded the title of Grandmaster by FIDE in 1987 and was named Estonian sportsman of the year in 1987 and 1989. Since 2006, he has represented the United States.

He was briefly a world top 10 player when, in 1991, he ascended to the number 5 slot on FIDE's official list with an Elo rating of 2650.

Jaan Ehlvest's brother, Jüri Ehlvest, was a well-known writer in Estonia.

Ehlvest studied psychology at Tatu State University. In 2004, Ehlvest published his autobiography, The Story of a Chess Player. In 2006, unsatisfied with the lack of support from the Estonian Chess Federation, Ehlvest decided to move to the United States; since then, he has been a member of the USCF and competed internationally for the USA.

In March 2007, Ehlvest accepted an invitation to play an unusual eight-game match against the chess program Rybka, one of the strongest chess programs in existence. He was playing Black in all games, but was given pawn odds (Rybka was playing each game a pawn down; different white pawn was removed in each game). He lost the match by 2½:5½ (+1−4=3). In a following rematch, the pawn odds were removed, Ehlvest was given White in every game, twice the time on the clock, and significant computational handicaps were placed on the machine. Ehlvest lost decisively, 1½:4½.