NFL Network Insider Ian Rapoport first reported the development.
The surgery is expected to sideline the rookie running back three to four weeks, Rapoport reported. There's a chance Penny won't return before Week 1 of the regular season. Carroll hopes he'll play in Week 1.
He was battling Chris Carson for the Seahawks' starting running back job prior to the injury, which he suffered during practice Monday. Penny flew to Philadelphia on Tuesday night and is scheduled to have surgery first thing Wednesday morning, Rapoport reported.
After trading back in the first round from 18 to 27, Seattle surprised many by making Penny the second running back selected in the draft. The Seahawks doubled down on the move by asserting they would have taken him at 18.
Penny (5-11, 220) was listed second on the team's most recent unofficial depth chart, ahead of Mike Davis and C.J. Prosise, among others. He rushed for just 16 yards despite a team-high eight carries in the Seahawks' preseason opener last week against the Colts.
The San Diego State product led college football in rushing last year with 2,248 yards.