Atlanta selected Alvarez's contract from Triple-A Gwinnett on Monday.
The 21-year-old will reach the big leagues for the first time after he slashed .293/.401/.417 with seven home runs and 21 stolen bases across 334 plate appearances between Gwinnett and Double-A Mississippi. Alvarez has played shortstop and third base during his minor-league career, but his athleticism and defensive instincts should allow him to emerge as an option at second base while Ozzie Albies (wrist) is sidelined, likely until the second half of September. Atlanta signed veteran utility player Whit Merrifield to also provide depth at second base, but Alvarez should get the first chance to fill in for Albies.