The 2000 American League Championship Series (ALCS) was a matchup between the East Division champion New York Yankees and the Wild Card Seattle Mariners. The Yankees had advanced to the Series after beating the West Division champion Oakland Athletics in the ALDS three games to two and the Mariners advanced by beating the Central Division champion Chicago White Sox three games to none. The Yankees won the Series four games to two and went on to defeat the New York Mets in the World Series to win their third consecutive World Series championship, 26th overall.

The American League Championship Series (ALCS), also known as the American League Pennant, is a best-of-seven playoff and one of two League Championship Series comprising the penultimate round of Major League Baseball's (MLB) postseason. The winner of the ALCS wins the AL pennant and advances to the World Series, MLB's championship series, to play the winner of the National League's (NL) Championship Series. The ALCS began in 1969 as a best-of-five playoff and used this format until 1985, when it changed to its current best-of-seven format.