Capable of playing right across the back row, McCusker joins the Ospreys after Sam Underhill underwent surgery on his shoulder that will sideline him for four months, and with several other back row forwards at various stages of their rehabilitation from injury and targeting a return to action over the coming weeks.
Head Coach, Steve Tandy, said:
"We are going into a very busy period, with two games against Leicester and a training camp in Belgium where we play their national team. With Sam's injury and one or two others working their way back to full fitness who are not quite there yet, we felt that we needed someone else in to help us through this period.
"We are fortunate to have someone with Rob's versatility and experience available and have brought him into the environment with a view to him helping us prepare for Zebre at home in the opening round of the PRO12 next month. He knows us, knows plenty of the squad and we know him well, and we know that the kind of character he is, he will be able to slot in and do a valuable job over the coming weeks while allowing us to ensure we don't rush anybody back too early."
Wrexham born McCusker spent 11 years with the Scarlets, making 133 appearances and scoring six tries, captaining the team between 2012 and 2014. Last October he switched to London Irish, playing 17 games for the Reading based side, 14 in the Aviva Premiership and 3 in the European Challenge Cup.
After representing Wales at age-grade and sevens, he made his full international debut against South Africa in Cardiff in 2010, winning six caps in all.
McCusker said:
"I'm really excited about joining up with the Ospreys ahead of the new season and can't wait to get stuck in straight away. Hopefully I'll be able to play a part over the coming weeks and make a good impression on the coaches, the other players, and the Ospreys supporters. I'm looking forward to being in a fresh, positive environment and a new challenge."
