Canseco's family left Cuba when he and his brother were infants, and he grew up in Miami, Florida, in the United States. Canseco did not attend college, having been drafted in the 15th round by the Oakland Athletics in 1982. He entered the major leagues in 1986 and was an immediate splash, being named the American League's Rookie of the Year after connecting on 33 home runs that year. In 1987, he was joined on the team by Mark McGwire, who hit 49 home runs that year, and together they became known as the "Bash Brothers." In 1988, Canseco became the first player in major league history to hit at least 40 homers and steal at least 40 bases in the same year. That year, he helped the Athletics to the World Series but they lost to the Los Angeles Dodgers in five games. Canseco was unanimously named the American League's Most Valuable Player in 1988.
In 1989, Canseco was injured most of the year, but he still managed to hit 17 homers as the Athletics won their first World Series since 1974, beating the San Francisco Giants in four games. The 1989 Series was interrupted before Game 3 by a major earthquake in the San Francisco Bay Area.
Canseco came back in full strength in 1990, hitting 37 homers and taking the A's to the World Series once again. But this time it was his team that got swept, losing to the Cincinnati Reds in four games. Canseco continued to be productive, but after 1991 when he hit 44 homeruns his career hit a plateau, never accomplishing what many expected he was capable of in the face of frequent injuries and controversy. In 1992 he was traded to the Texas Rangers, the first of many junkets around the league.
In 1993, Canseco received unwanted attention when, during a game against the Cleveland Indians, Carlos Martínez hit a fly ball that Canseco lost in the lights. The ball hit him in the head and bounced over the wall for a home run. That same season, Canseco suffered further indignity and ridicule when he asked to pitch during a runaway loss; he injured his arm, underwent Tommy John surgery, and was lost for the remainder of the season.
Canseco's personal life has also had its troubles. In 1989, his first wife, Esther Haddad, whom he married in November 1988, accused him of domestic violence after he allegedly ran his car into hers. That was the beginning of a series of accusations and run-ins with the law, including a confrontation with teammate Uri Snir, while Canseco was in the public spotlight. He divorced in 1991 and remarried in August 1996, to Jessica Sekely; he was arrested in November 1997 for allegedly hitting her. In January 1998 he was sentenced to probation and required to have counseling. The couple divorced in 1999. In October 2001, he and his brother got into a fight with two California tourists at a Miami Beach nightclub that left one man with a broken nose and another needing 20 stitches in his lip; Canseco was charged with two counts of aggravated battery. In 2005, his ex-wife, using the name of Jessica Canseco, was featured in the September issue of Playboy magazine.
Canseco did have a productive season again in 1998, in which he hit 46 home runs and stole 29 bases, the most he had stolen since the 40 he stole in 1988. He was a Blue Jay that year, but his comeback was missed by most fans because of the home run race in the National League between Mark McGwire and Sammy Sosa. Canseco then went to Tampa Bay, where he was having a tremendous home run season (34 in 114 games; and was voted an All-Star) when he injured his back and was lost for the season. He was traded to the New York Yankees down the stretch in 2000, but was not a factor at all in the postseason.
Cover of JuicedJose played sparingly with the Chicago White Sox in 2001, after being cut by the Anaheim Angels in spring training and spending half of the season with the Newark Bears of the independent Atlantic League. In 2002, Canseco was signed by the Montreal Expos but was released prior to the regular season. Canseco retired in May of that year after a string of injury-filled seasons. Canseco made a brief comeback attempt in 2004, but was not offered a spot with the Los Angeles Dodgers after a spring tryout. His 462 career home runs rank him 26th on the all-time list. Canseco was at one time the all-time leader in home runs among Latino players; he was later surpassed by Rafael Palmeiro and Sammy Sosa.