The Ireland skipper will reach the milestone 11 years after making his Test debut, with Gatland the coach who gave the then 20-year-old his first taste of international rugby.
Gatland was in charge of Ireland from 1998 and 2001 and it was he who picked the young Leinster prospect for the summer clash with Australia in Brisbane.
The New Zealander has since worked with O'Driscoll on the 2009 Lions tour of South Africa and he admits he has nothing but admiration for one of the greatest players of the current generation.
"He deserves all the accolades, and I will be one of the first to stand up in the coaching box on Saturday and clap him," said Gatland, whose Wales side will arrive at Croke Park looking to bounce back from a narrow defeat to France.
"I am absolutely delighted for him and proud I have had an association with him.
"I gave him his first cap, and it was an honour for me to be involved with him with the Lions last year to see how he has developed.
"I was incredibly impressed with his leadership and his understanding of the game. He was one of the main reasons Jamie Roberts ended up having such a good tour.
Unsurprisingly, Gatland highlights Ireland's Six Nations win over France 10 years ago as his most vivid memory of O'Driscoll's glittering playing career to date.
O'Driscoll announced himself on the world stage that day in Paris thanks to a sublime hat-trick of tries that helped Ireland to a landmark victory.
"That is my greatest memory of Brian - the hat-trick of tries he scored when Ireland beat France in Paris for the first time in 27 years," added Gatland.
"I remember the French great Philippe Sella coming into the changing room to congratulate him afterwards and saying it was one of the most impressive centre performances he had ever seen.
"Brian has got natural flair, is a good passer off both hands, has got a step and fantastic pace.
"He would most definitely be in most people's World XV of the last decade."