Cueto, who had season-ending Tommy John surgery a year ago, threw 49 pitches in 2⅔ innings in his third rehab start at Class A San Jose on Thursday and is scheduled to throw 55-60 pitches in his next outing.
Manager Bruce Bochy acknowledged earlier in the day that the team would "reevaluate" its timeline for activating Cueto, whom he said was "pretty close to 100%." The Giants' original plan was for Cueto to make at least two more rehab starts after his outing Thursday, but that could change.
After the Giants' 7-0 win over the Arizona Diamondbacks on Thursday night, Bochy said of Cueto, "The way he is throwing, he will be pitching for us in September."
Cueto went 3-2 with a 3.23 ERA in nine starts last season before the injury. He is in the fourth year of a six-year, $130 million contract.
Cueto struck out seven in four scoreless innings in his first two rehab appearances in the rookie Arizona League.
San Francisco (61-61) is 3½ games back in the NL wild-card race.
The Associated Press contributed to this report.