The left-hander allowed three runs on seven hits and two walks while fanning seven batters over 7 2/3 innings in Class A Advanced San Jose's 4-2 loss to Bakersfield.
The 2002 American League Cy Young Award winner yielded two runs on a pair of singles and Brodie Greene's homer in the first inning before settling down and holding the Blaze hitless over the next three frames.
The 33-year-old left the bases loaded in the fifth, but he surrendered a run on consecutive two-out hits to Devin Lohman and Jorge Jimene in the sixth inning. He was perfect in the seventh before turning things over to the San Jose bullpen with two outs and Alex Buchholz on second base in the eighth.
A veteran of 12 Major League seasons, Zito (2-1) first sprained his foot after lunging for a ball in the second inning of San Francisco's 5-3 win over Arizona on April 16 this year.
He made two previous appearances with San Jose earlier this year. He allowed a run on two hits while striking out six in a 7-1 win over the Stockton Ports in his first start June 6 and he yielded three runs -- two earned -- on six hits and three walks over seven innings five days later in an 8-3 win over the Modesto Nuts.
Zito then made two starts with the Triple-A Fresno Grizzlies in the Pacific Coast League, the latter of those a nine-inning two-hitter for a 2-0 victory over the Salt Lake Bees on June 21.
Zito returned to San Francisco's 25-man roster a week later, earning three consecutive wins in his return. Since then, however, Zito has struggled, surrendering 19 runs in losses to San Diego, Philadelphia and Cincinnati. He was placed back on the 15-day disabled list with a recurrence of the foot sprain Aug. 1.
He has pitched just 49 2/3 innings over nine Major League starts this season. He had thrown at least 180 innings and made 32 starts in each of his previous 10 seasons between Oakland and San Francisco.
On Monday, Tim Crabbe (4-3) earned the win for Bakersfield, scattering three hits and walking two while striking out eight over six scoreless innings.