[citation needed] He attended Cal State Northridge, where he played shortstop for the Matador baseball squad.

[4] In the 2000 offseason, the Cardinals signed former All-Star Fernando Viña to start at second base, making Kennedy, who hadn't separated himself from his infield counterparts, expendable.

On March 23, 2000, Kennedy was traded to the Anaheim Angels along with All-Star pitcher Kent Bottenfield for outfielder Jim Edmonds.

During the regular season, he hit .312/.345/.449 with 7 home runs and 52 RBIs, as the Angels earned a wild card berth, their first playoff appearance in 16 years.

In Game 5 of the 2002 American League Championship Series against the Minnesota Twins, Kennedy hit three home runs, joining only nine other players who hit three homers in a postseason game: Babe Ruth, Bob Robertson, Reggie Jackson, George Brett, Adrián Beltré, Albert Pujols, Pablo Sandoval, Jose Altuve, and Enrique Hernández.

The 2003 season was a season of ups and downs for Kennedy, he hit a career-high 13 home runs, and his walk rate increased over 5% (3.7% in 2002 to 8.8% in 2003), but his average dropped to .269 and he struggled to repeat his 2002 success as the Angels failed to make the postseason and defend their World Series title.

On September 20, during a game against the Seattle Mariners, Kennedy suffered a torn ACL & MCL in his right knee while attempting to field a single up the middle from Ichiro Suzuki,[10] which caused him to miss the remainder of the season, including the Angels final playoff push and eventual playoff run.

Kennedy's 2006 campaign was one filled with many question marks, as statistically he was closer to his numbers in his 2003 & 2004 seasons than his peaks in 2002 & 2005, as he hit .273 with 4 home runs and 55 RBIs.

[11] While the rumors never came to fruition, Kennedy was forced to share the starting second base position, playing in a platoon with the rookie Kendrick for the remainder of the season.

The national spotlight shone briefly on Kennedy on August 16, 2006, when he took part in a bench-clearing brawl in the ninth inning of a game between the Texas Rangers and the Angels.

[12] Tensions between the two division rivals were already high, as two Rangers starting pitchers — Adam Eaton and Vicente Padilla — had been ejected in previous games that month for throwing at Angels batters.

Also, two Angels hurlers (Kevin Gregg and Brendan Donnelly) had already been thrown out of the game for hitting batters, and manager Mike Scioscia and bench coach Ron Roenicke had been ejected as well.

Rangers pitcher Scott Feldman hit Kennedy in the buttocks with a fastball with only one out remaining in the game, and his team up 9–3.

[16] On August 11, 2007, Kennedy was placed on the 15-day disabled list with a torn medial meniscus in his right knee, an injury that would sideline him for the remainder of the season.

Following the season, Kennedy requested a trade, stating that his desired role as a starter was not being fulfilled as the Cardinals acquired Felipe López to play second base down the stretch.