The defender, 32, who suffered an ankle injury against Championship rivals Reading in August, managed to get 45 minutes under his belt before being replaced at half-time.
Speaking to www.seagulls.co.uk after the game, Rosenior said: "It was great to be back out there. It’s been a long time and the injury was the most serious one of my career by far.
“The biggest thing was being back out there on the pitch, then you get a true guess at how you truly feel, and for me, I felt great."
Rosenior adds to the list of Albion returnees, with winger Solly March making a recent impact after nearly a year out, and Beram Kayal scored on his return in the FA Cup at the weekend.
The full-back added: "I’ve obviously been out for a long time but I felt fit, there was no pain, which was the biggest obstacle for me. Now I can look forward to being part of the squad again, and hopefully helping us achieve what we want to."
Brighton's under-21 squad were unable to reach the quarter-finals of the Checkatrade Trophy, succumbing to a 3-0 defeat against League One Coventry, despite an inspired performance from Albion goalkeeper Robert Sanchez, who produced some fine saves in the first half.
In spite of the loss, former Hull City man Rosenior was in full praise of his young teammates: "It goes to show the strength of this club, not only are we doing well at first-team level, but the younger teams are holding their own against quality teams.
"The experience has been fantastic for the young players and they’ll be better players for it."
Ruben Lameiras gave Coventry the lead on 41 minutes, before George Thomas made it 2-0 early in the second half. Ryan Haynes added a third for the Sky Blues two minutes from time.
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