He played in Major League Baseball (MLB) for the Texas Rangers, New York Mets, and San Francisco Giants.

[1] The Texas Rangers acquired Arias on 23 March 2004, completing a trade made 36 days earlier on 16 February that sent Alex Rodriguez to the New York Yankees for Alfonso Soriano.

[2] Among five Yankees prospects offered to the Rangers, Arias was selected over Robinson Canó because he was a more polished defender and two years younger.

The two-run homer off Milwaukee Brewers starting pitcher Shaun Marcum gave San Francisco a 4–0 lead in the 4th inning of a game the Giants would go on to win by a score of 6–4.

[8] On 13 June 2012, playing third base, Arias fielded a tricky grounder by Jason Castro, who was pinch-hitting for Xavier Cedeño.

Arias, stumbling backwards as he gloved the ball, quickly threw the baseball to first base for the final out of Matt Cain's perfect game.

On 10 October, during the Division Series against the Cincinnati Reds, Arias entered the game in the fourth inning and had two hits in three times at bat.

In the 2014 postseason, Arias appeared in 8 games, batting 2-for-4 with one RBI and two runs scored, as the Giants won the 2014 World Series over the Kansas City Royals.