The 32-year-old Myers has started major league games at first base, third base and each of the outfield spots. He is a .254 hitter with 153 homers and 521 RBIs in 1,063 games.
Cincinnati went 62-100 last season. It was its first season with at least 100 losses since it went 61-101 in 1982.
The Reds also announced the signing of catcher Curt Casali, 34, on a one-year deal and designated veteran third baseman Mike Moustakas for assignment. Casali, who played three years in Cincinnati, will back up Tyler Stephenson.
Myers could be used in the outfield with the Reds. He also could see some time at first while Joey Votto works his way back from rotator cuff surgery.
Myers hit .261 with seven homers and 41 RBIs in 77 games in his final season with the Padres. He was 3 for 29 in 10 playoff appearances.
Myers’ $20 million option was declined by San Diego last month, and he received a $1 million buyout that completed an $83 million, six-year contract.
Myers was selected by Kansas City in the third round of the 2009 amateur draft. He was traded to Tampa Bay in a multiplayer deal in December 2012.
The North Carolina native was the AL Rookie of the Year in 2013, hitting .293 with 13 homers and 53 RBIs for the Rays.
Myers was shipped off to San Diego in a three-team trade in December 2014. He hit 28 homers and finished with a career-best 94 RBIs and 28 steals in 2016, earning his only All-Star selection.