Baldwin enjoyed a breakthrough campaign in 2012/13, a season which saw him featuring regularly in the RaboDirect PRO12 as well as gaining his first Heineken Cup experience.
Baldwin has been with the Ospreys since January 2009 when his form in the Welsh Premiership with hometown club Bridgend was rewarded with a first regional contract. He made his Ospreys debut two months later, coming off the bench against Leinster at the Liberty Stadium.
After a loan spell in Italy with the Ospreys partner club ASR Milano, Baldwin returned to Wales at the start of 2012 and was heavily involved in the end of season run-in to a fourth league title, coming off the bench in the dramatic final win over Leinster.
Speaking after putting pen to paper, Baldwin said: "I'm really pleased. The Ospreys have been really great to me since I came on board four years ago and I've really developed.
"Last season was a big jump forward for me, being involved regularly week in, week out, and I'm happy that everything is sorted so that I can look forward to the new season and working with a great bunch of boys in the team and great coaching staff.
"The good thing about the Ospreys is the way they bring players through each year, not just youngsters but boys from the Premiership who haven't been part of the age-grade set-up. It shows there is talent beyond the age of 20 or 21 and if you work hard then the Ospreys will give you a chance.
"I was lucky enough to get an opportunity and I hope I've been able to make the most of it."
Andy Lloyd, Rugby Operations Manager at the Ospreys, added: "Scott has been outstanding for the region over the last 18 months and has earned this contract with his hard work, effort and dedication.
"He's worked really hard over a number of seasons to improve both his physicality and his technical skills and remained patient when at times he found a lack of game time frustrating.
"Scott has shown that if you put the hard work in you can get the reward. The challenge for him now that he has secured a new contract is to continue working hard and to strive for continuous improvement rather than just settling for what he's got."
Ahead of the new season, Baldwin added that he's looking forward to working with Chris Gibbes, the new forwards coach at the Ospreys.
"Chris has come in, taken a few sessions and it's going to be good to see where he takes the forwards this season," he said.
"I'm just proud to be part of it for the next few years."