The 31-year-old sustained the injury early in the 38-28 victory on Saturday night and bravely tried to play on before coming from the field in the 12th minute.
Initially the Broncos medical staff thought he had injured an AC joint but a scan revealed a collarbone fracture and he had surgery on Sunday.
The Broncos have not as yet provided a timeline on his return but he will miss the away clash with Newcastle on Sunday and possibly the rest of the regular season at least.
Gosiewski had earlier missed 10 weeks with a broken arm. He has been a strong performer in 2025 with the side winning 10 of the 14 games he has played.
Brisbane are on track to play finals but they have started to lose key forwards. Young guns Xavier Willison (broken arm) and Ben Te Kura (foot) are both still unavailable
Back-rower Brendan Piakura has not played the past two weeks after a concussion at training, one of several head knocks he has had this season.
He is still going through protocols and the Broncos will make a call on his availability in the coming days.
The Broncos do still have Jaiyden Hunt who came off the bench against the Dolphins and can play on an edge or in the middle.
Brisbane received stellar displays from fullback Reece Walsh, half Ben Hunt and prop Payne Haas after trailing 28-14 against the Dolphins.
The Broncos will train at Red Hill on Tuesday before travelling to Newcastle on Wednesday for a training camp ahead of their showdown with the battling Knights.
Hunt, in his favourite No.7 position due to the absence of injured skipper Adam Reynolds, had three try assists. Walsh was man of the match for his best game of the season and Haas was a powerhouse when he came on for his second stint.
"Hunt's presence with the group as the general was good I thought," coach Michael Maguire said.
"Our leaders ... I think that's something I've really seen a growth in us as a team.
"They're driving it, that's the best part about what I'm seeing at the moment, and the more they keep driving the better we're going to become.
"I think Hunt was able to just capitalise on being able to do his role and like Reece he played his part. Payne came on and changed the momentum of the game. He flipped that for us but they're all playing their part and if they're doing their jobs for each other I guess I'm pleased."
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