Eovaldi (3-5) scattered seven hits and two walks in the 102-pitch performance, lowering his ERA to 3.40. He recorded six strikeouts.
Mathis smashed a solo homer in the second for a 2-0 Miami lead and capped the scoring with a two-run double in the third.
Ed Lucas added a two-run single for the Marlins, who snapped a six-game skid.
Braves starter Alex Wood (3-3) was pounded for seven runs on eight hits in just 2 1/3 innings.
National League East-leading Atlanta's six-game winning streak came to an end.
Swim Week Miami Beach 2014 [PHOTOS]