He was traded by the Padres on December 4 to the Detroit Tigers for Dave Campbell and Pat Dobson. In three seasons with Detroit, he went 21–22, having his best season in 1970 by going 12–13, although he had a 4.06 ERA in 213 innings, with a high of 101 strikeouts. He threw 122 innings in the next season and just 47 in the following. He was selected off waivers by the Atlanta Braves on August 7, 1973. Niekro used a fastball and a slider early in his career, with mixed results. In his two seasons with the Braves, he went a combined total of 5–6 while having a 3.76 ERA and 67 innings pitched. During his tenure, he got re-acquainted with the knuckleball that their father taught them. The knuckleball became an essential part of his arsenal though never his sole pitch. Joe threw harder than Phil and could set up batters nearly as effectively with his fastball in combination with his excellent changeup.