The Dutch under-21 international joined Albion from Heerenveen last month but has spent the last few weeks on Olympic duty in Beijing.
"I spoke to Gianni the other day and watched his game from the other night," Mowbray told the Birmingham Mail. "It was great to see a West Bromwich Albion player playing in such an arena and such a game, against such great players.
"It was a great atmosphere and there some of the best players in the world on the pitch. I watched him walk on the pitch alongside Lionel Messi and Riquelme - full Argentina internationals and great, great players.
"It was quite special and hopefully the Premier League arena will hold no fears for him after playing in games like that.
"The reason he is here because we identified he is a very good player and we are looking forward to getting him back into the squad and back into contention for a place in the team."
Mowbray was clearly impressed with his performances in Beijing.
"Gianni did exceptionally well," he added.
"He was fast, athletic and comfortable on the ball. The Dutch should have won it in the last couple of minutes of the game. They missed a great chance and it went to extra time and ultimately paid the price.
"For the boy, it would have been a great occasion for him to play in the semi-final of the Olympics against Brazil.
"But I'm glad for myself and the team that he is on his way back and will be back in training on Thursday."