Lasker was shocked by the poverty in which Wilhelm Steinitz died and did not intend to die in similar circumstances. He became notorious for demanding high fees for playing matches and tournaments, and he argued that players should own the copyright in their games rather than let publishers get all the profits. These demands initially angered editors and other players, but helped to pave the way for the rise of full-time chess professionals who earn most of their living from playing, writing and teaching. Copyright in chess games had been contentious at least as far back as the mid-1840s, and Steinitz and Lasker vigorously asserted that players should own the copyright and wrote copyright clauses into their match contracts. However Lasker's demands that challengers should raise large purses prevented or delayed some eagerly-awaited World Championship matches — for example Frank James Marshall challenged him in 1904 to a match for the World Championship but could not raise the stakes demanded by Lasker until 1907. This problem continued throughout the reign of his successor Capablanca.

Some of the controversial conditions that Lasker insisted on for championship matches led Capablanca to attempt twice (1914 and 1922) to publish rules for such matches, to which other top players readily agreed.

Lasker was also a mathematician. In his 1905 article on commutative algebra, Lasker introduced the theory of primary decomposition of ideals, which has influence in the theory of Noetherian rings. Rings having the primary decomposition property are called "Laskerian rings" in his honor.

His attempt to create a general theory of all competitive activities were followed by more consistent efforts from von Neumann on game theory, and his later writings about card games presented a significant issue in the mathematical analysis of card games.

However, his dramatic and philosophical works have never been highly regarded.

Lasker was a good friend of Albert Einstein, who wrote the introduction to the posthumous biography Emanuel Lasker, The Life of a Chess Master from Dr. Jacques Hannak (1952). In this preface Einstein express his satisfaction at having met Lasker, writing:

Poetess Else Lasker-Schüler was his sister-in-law. Edward Lasker, born in Kempen (Kępno), Greater Poland (then Prussia), the German-American chess master, engineer, and author, claimed that he was distantly related to Emanuel Lasker. They both played in the great New York 1924 chess tournament.

The following table gives Lasker's placings and scores in tournaments. The first "Score" column gives the number of points on the total possible. In the second "Score" column, "+" indicates the number of won games, "−" the number of losses, and "=" the number of draws.

Here are Lasker's results in matches. The first "Score" column gives the number of points on the total possible. In the second "Score" column, "+" indicates the number of won games, "−" the number of losses, and "=" the number of draws.