The gruesome break happened in the final minutes of Sunday's 40-21 loss to the 49ers.
Butler was injured while catching a 2-yard touchdown pass late in the fourth quarter. He was hit from each direction by defenders. His leg snapped and wiggled at an awkward angle before trainers and medics tended to him in the end zone. Butler was taken off by cart with his leg placed in a vacuum air splint.
He underwent surgery Sunday night at Stanford Hospital, where a rod was inserted to stabilize the break. Carroll said only one of the two bones in the lower leg was broken but that it broke in two spots.
Butler will remain in the Bay Area for a few days to begin his recovery.
"It was able to go right back together nicely," Carroll said. "It's a real intricate surgery and all that but they were pleased with the result of it."
Butler's injury further depletes Seattle's receiving corps. The Seahawks played Sunday without their top two receivers, Mike Williams and Ben Obomanu, due to injuries, although Carroll was optimistic Monday that both would practice and play this week against Atlanta.
Carroll said they had not figured out how they will fill Butler's roster spot.
Butler is in his second season with the Seahawks and started eight games earlier in the year before being passed by Obomanu and moving into a reserve role. Butler had 36 catches for 385 yards and four touchdowns.
"Everything went really well and he should be able to have a really good recovery. It was a very serious break," Carroll said. "We're still thinking about him. He'll be back in a couple of days."