Wales have seen their second row ranks considerably depleted ahead of their RBS 6 Nations opener against Ireland on February 2 with Luke Charteris, Bradley Davies and Alun Wyn Jones all missing.
And Kohn admits he's ready to answer the call.
"Receiving the call-up was surreal and I can't wait to join up with the squad this weekend," he said.
"It's a really proud moment for me and a great opportunity to show what I can do.
"It will be good to meet the squad, get training and hopefully be part of a successful Six Nations campaign with Wales."
And while Kohn was overlooked for Wales' initial squad, head coach Rob Howley admitted he had been keeping a watchful eye on the lock forward.
"We looked at Olly when we initially selected the Six Nations squad and we have brought him in now as we believe he will be an experienced addition," said Howley.
"He has been performing very well for Quins and has been a feature in their pack.
"He's a strong ball carrier and dominant at the set piece and it will be good to see him in the international environment."