Motlop was one of the competition's most improved players last year, but has had endured an interrupted pre-season with ongoing knee problems.
After seeing a specialist in London, Motlop underwent a 'minor procedure' that is expected to rule him out of training for six to eight weeks.
Given he will need time to recover, the Cats are likely to be without one of their most exciting players for opening few rounds of the season.
"The assessment was that Steven would benefit from minor corrective surgery, and he underwent this while he was in London," Geelong head of sport science and medicine Peter Stanton said.
"The operation was successful and we expect that Steven will be back training is six to eight weeks."