The Netherlands international has hailed the midfielder's influence, while has also taken the time to praise Philipp Lahm
The Germany international missed the games against Chelsea and Hannover due to an ankle problem, but made his comeback against CSKA Moscow last week with a 20-minute cameo before returning to the starting XI again versus Schalke at the weekend.
"Schweinsteiger's return is very important for us," Robben was quoted as saying by TZ.
"We have a number of key players and Bastian is one of them. Plus he's obviously our vice-skipper. The 1-0 he scored against Schalke was a crucial goal as well."
Robben then went on to hail Philipp Lahm's versatility, with the Bayern skipper having filled a midfield role during Schweinsteiger's absence.
"I like Philipp in midfield. He's the kind of player who can play in any position.
"He's got excellent technique and is very intelligent. He is a versatile player and has shown this time and time again."