
The 33-year-old helped Santos beat fourth division Agua Santa 3-1 in a Sao Paulo state championship match.
Neymar, who failed to score in his first three games, stepped up to slot home a penalty in the 14th minute.
It was his 137th goal in 229 appearances for the club he has returned to after leaving them in 2013 for Barcelona.
It was also his first goal for anyone since Oct 3, 2023, when he was playing for Al Hilal against Nassaji Mazandaran in the Asian Champions League.
He terminated his contract with the Saudi club at the end of January to return home.
Neymar spent 18 months with Al Hilal after joining from Paris Saint-Germain in August 2023 on a deal that enriched him by a reported €100 million (US$103 million) a season.
Neymar played five games for them before suffering a serious knee injury playing for Brazil.
After a year out, he returned last October and made two more appearances for Al Hilal, only to suffer a hamstring tear.
Yesterday, in addition to his goal, Neymar also provided an assist, another first in the four matches he has played since arriving in Brazil.