Trained by Gordon Elliott and owned by Giggnstown House Stud, the seven-year-old ran on strongly in the closing stages to repel the sustained challenge of 8/1 chance Kilfilum Cross, recording a length and three-quarter win, which was also the gelding's first victory over fences.
James has ridden over 200 winners on the Irish point-to-point circuit and said: "I have always dreamed of this and it is unbelievable. The horse took me everywhere and jumped everywhere. Gordon is a genius and I am just grateful to Gigginstown for giving me the ride. I can't believe it.
"I was jumping and actually getting there a bit too soon, so I held on to him the whole way down the hill until I got going to the second last.
"He has just taken off with one slap down the neck, winged the second last and was gone. He was pricking his ears going to the line and had loads left.
"The further he was going, the better he was going, and he had loads left coming up the hill.
Gordon Elliott was recording a 549/1 treble on day three of The Festival and he paid tribute to James.
The Cullentra maestro said: "I am delighted for Rob James, who is a great fella. He is one of the top point-to-point riders and a nice fella too.
O'Leary said: "He's a very valuable seven-pound claimer. He almost never rides on the track, but he's ridden hundreds of point-to-point winners. He gave that a fantastic ride."
What a moment!
— Racing TV (@RacingTV) March 12, 2020
Rob James won't forget this one for a while. Cracking ride %uD83D%uDC4F #CheltenhamFestival pic.twitter.com/w7cTDA0Gww