Martínez spent his final season in 1998 with the Atlanta Braves. He went 4–6 with a 4.45 ERA, appearing in 53 games while making five starts and having two saves within 91 innings. He had 62 strikeouts and 19 walks. He made four appearances in the postseason for the Braves, all in the NLCS against the San Diego Padres. He received the win for Game 4, getting the final out of the 6th inning in relief of Denny Neagle by having Chris Gomez ground–out before the Braves scored in the next inning. His final appearance was in Game 6 on October 14, replacing John Rocker in the top of the 6th inning. He retired all four batters he faced, although the Braves lost the game 5–0 along with the series.