Born and raised in Tacoma, Washington, Cey was a multi-sport athlete at Mount Tahoma High School, its first to earn nine varsity letters. Following graduation in 1966, he attended Washington State University in Pullman and was a member of Phi Delta Theta fraternity. Cey played two years of college baseball for the Cougars, on the freshman team in 1967, and a year on the varsity under head coach Brayton in 1968. He was selected in the second phase of the 1968 MLB Draft in June.
With the Dodgers, third baseman Cey was part of an All-Star infield that included Steve Garvey (first baseman), Davey Lopes (second baseman) and Bill Russell (shortstop). This quartet was the most enduring infield in baseball history[citation needed]. The four infielders stayed together as the Dodgers' starters for eight and a half years. Cey was one of the most productive and adept-fielding National League third basemen in the 1970s, but was overshadowed by Pete Rose and Mike Schmidt. In 1977, he helped the Dodgers to a fast start by batting .429 in April with a record-tying 11 home runs for the month and 29 RBIs. The Dodgers won the Western Division title that season on their way to the National League pennant.
Cey continued to have productive seasons with the Dodgers, helping them to pennants in 1978 and 1981. After the 1982 season, the Dodgers traded Cey to the Chicago Cubs for two minor leaguers so that Pedro Guerrero could move to third base and rookie Mike Marshall could get in the Dodgers' outfield. Cey provided veteran leadership for the Cubs over four seasons and, in 1984, helped lead the Cubs to the National League East Division title, hitting 25 homers and driving in 97 runs, both team highs. Cey spent the final year of his career in 1987 as a part-time player with the Oakland A's.
In a 17-season career, Cey was a .261 hitter with 316 home runs and 1139 RBI in 2073 games.
Cey had a terrific 1981 World Series in which he helped spark the Dodgers to four straight victories after they had lost the first two games, including returning for the clinching Game 6 after having been being hit in the head by a Goose Gossage fastball during Game 5. Cey was named co-MVP along with Steve Yeager and Pedro Guerrero. He is still a part of the Dodgers' organization and continues to make appearances on the team's behalf.