21-year old Grabham is a product of the Ospreys' development pathway, starting off in community rugby playing for local club Tondu before graduating through the system to represent Bridgend District and play age-grade rugby for the region.
He then gained his first senior experience with Bridgend Ravens, helping them win promotion to the Premiership in 2010/11 before featuring regularly for the club last season.
He has put pen to paper on a two-year deal that runs until the summer of 2015, and will continue to combine his fledgling rugby career with his university studies as he completes a BSC in Biochemistry.
"I'm really happy to sign for another two years" said Grabham after the new contract was signed.
"It's my home region and it's a good environment to be in as a developing player. This has been my first full season and I've enjoyed it. I've played a few games, I've been fortunate enough to get the opportunity to be involved in some big matches and I want push on from here, between now and the end of the season and then next year.
"I've settled well into the group and I think I've done well when I've been given a chance on the wing. It's been a good season for me so far, I'm really enjoying myself, now it's important that I keep improving. I've got another two years and I want to make the most of it."
Grabham made his senior regional debut last season in the LV= Cup game away to Exeter Chiefs, finishing the campaign with three substitute appearances to his credit.
This season has seen him feature regularly for the Ospreys, with 10 more appearances to his credit, his first start coming against Glasgow in the PRO12 in September and his Heineken Cup debut away to Treviso two months ago.
He has also gained international experience with Wales, captaining his country on the IRB Sevens World Series.
Rugby Operations Manager at the region, Andy Lloyd, said:
"Tom is an up and coming young player who has already made an impression when given the chance to play for the region on the wing.
"He's a very intelligent young man who understands his roles and responsibilities and is very diligent in everything he does which will stand him in good stead if he is going to progress and establish himself fully as an Osprey. He works his socks off and ultimately is a very professional rugby player who is developing the right habits on and off the field.
"He's got great feet, he's powerful, and he understands what we want from him as a wing. This isn't just about the here and now, this is good news for the future as we have secured the services of a real prospect from within the region for the next two years."
This is the latest good news for the Ospreys in terms of players signing new deals with the region, as Grabham becomes the seventh player to commit recently after Tom Isaacs, Duncan Jones, Rhys Webb, Joe Bearman, Lloyd Peers and James King.
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