The 32-year-old moved from Paris Saint-Germain in a blockbuster deal in August 2023 but played only five matches before rupturing his meniscus and anterior cruciate ligament on international duty in October.
"Happy to be back in the group," Neymar posted on Instagram, with pictures of him running and kicking the ball, watched by Al Hilal's Portuguese coach Jorge Jesus.
After surgery, Neymar resumed individual training in July. His return to competitive games will depend on "his technical readiness and the coach's decision", a club official who asked to remain anonymous told AFP.
Brazil coach Dorival Junior urged patience for Neymar's recovery last week as he left the forward out of his squad for the upcoming 2026 World Cup qualifiers against Chile and Peru.
Al Hilal, the reigning Saudi champions, have not yet registered Neymar for the current Saudi Pro League season, which began last month.
But the former Barcelona player, with a reported salary of about 100 million euros (£83.6m) a year, is listed to play in the AFP Champions League, Asia's biggest club tournament.
Despite Neymar's absence, Al Hilal won the Saudi league at a canter last season, going unbeaten with 31 wins and three draws.
The Riyadh club also clocked up a record 34 consecutive wins in all competitions before being stopped in the Champions League semi-finals by the UAE's Al Ain.
