"We are delighted that Gavin feels ready to resume his career," said Ospreys Coach Lyn Jones. "His bout of illness didn't help but I am hoping to see him play some part against the Scarlets.
"His last game for us was in January against Ulster and, when players have been out of action for a long time, it takes a while to get back into the swing of things.
"There is always a lot of expectation on Gavin, but there is no pressure on him from us. It is important he gets some game time under his belt because he has been working really hard and now feels 100 per cent fit.
"He is looking forward to Tuesday and he is excited at the prospect of getting back into action with the Ospreys."
The Ospreys, who won the Magners League title for the second time last season, have gone 18 games in all competitions without defeat at the Liberty Stadium over the past 15 months. Included in that winning streak is a Boxing Day triumph over the Scarlets in front of a sell-out crowd.
Phil Davies's Scarlets outfit reached the semi-finals of the Heineken Cup last season but, like the Ospreys, ended up on the losing side last weekend when they were beaten at home by the Dragons.
Ospreys (from): L Byrne, S Terblanche, G Henson, M Taylor, G Owen, A Bishop, M Roberts, J Vaughton, S Connor, J Marshall; T James, R Hibbard, B Williams, A Millward, C Griffiths, B Cockbain, M Powell, A Lloyd, L Bateman, M Collins, R Pugh, T Smith, B Lewis, F Tiatia