The Brazil forward has not played since sustaining the injury during his nation's CONMEBOL World Cup qualifier against Uruguay in October last year.
He suffered an anterior cruciate ligament (ACL) injury and underwent surgery in November.
Having moved to Saudi Arabia from French champions Paris St Germain for a reported fee of around 90 million euros in August last year, Neymar had only played five games before his layoff as he was struggling with muscle injuries.
The former Barcelona forward, who is Brazil's leading scorer, missed their 2024 Copa America campaign in the United States, where they suffered a second straight quarter-final exit from a major tournament after losing to Croatia on penalties at the 2022 World Cup.
"Al Hilal is happy to announce that Neymar will join the squad for the away trip to Al Ain. He's back," the club posted on social media platform X.
"Neymar participated in team training after completing his recovery program," Al Hilal said in another post.
They play Al Ain at the Hazza bin Zayed Stadium on Monday.