Neymar signs for Santos
"The contract is for six months initially, but obviously we will do all we can that he remains with us," Santos's vice-president Fernando Bonavides told Canal SporTV.
"What we are hoping is that he remains with us until next year's World Cup."
The 32-year-old former Barcelona and Paris Saint-Germain forward returns to Santos after playing just seven times for Saudi Arabia's Al Hilal despite a reported salary of around $104 million a year.
Neymar, Brazil's all-time top scorer, joined Al Hilal in August 2023, following fellow superstars Cristiano Ronaldo and Karim Benzema to the Gulf.
But two months after his arrival in Riyadh, he ruptured a cruciate ligament in his left knee while playing for Brazil in a 2026 World Cup qualifier, which kept him on the sidelines for a year.
He then suffered a series of hamstring and knee injuries as he tried to return to action.
Neymar cut a contented figure as he was presented to fans in a ceremony at the club's Estadio Urbano Caldeira, featuring concerts by several local music stars.