Rubaud and Harry Cobden made every yard to justify favouritism in the Coral Scottish Champion Hurdle at Ayr.
The 7/2 favourite was last seen winning the Grade Two Sky Bet Dovecote Novices' Hurdle at Kempton in February and proved a step ahead of the assessor on his second start in handicap company.
He failed to get competitive in the Betfair Hurdle on his penultimate start but was far more at home in this smaller field, dominating from the offset.
Anna Bunina, last year's winner and runner-up two seasons ago, moved through on his inside travelling strongly but she could only stay on at the one pace as Cobden asked Rubaud to quicken in the straight and it was left to Colonel Mustard to throw down the strongest challenge from off the pace.
Rubaud kept finding, though, and had three lengths to spare at the line.
"He was very good," Cobden told ITV Racing.
"He's definitely better right-handed, all the way down the back he was hanging right and I actually edged out into the middle of the course because the more I was down on the inside, the more he was hanging. Going round that top bend, I actually took my right hand off the rein and had two on my left (rein) just to try and get him round there as tight as possible.
"He's a lovely horse. He'll be a good chaser next year."
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Winning trainer Paul Nicholls added: "That was a fantastic ride. He's not the easiest to ride, he's a bit keen but he's beginning to relax. He went all the way up to Aintree last week but didn't run because the ground had gone soft.
"He jumps brilliant for a novice and he will be a fantastic chaser. It's amazing how they can improve over the summer and he's only a young horse so we might just start over hurdles (next season) and see where we end up.
"He is in next Saturday at Sandown in a £100,000 novice handicap hurdle. I'll look at the weather forecast and if it's a dry week and we're happy, that's an option."
Nicholls, who will be crowned champion trainer at Sandown next weekend, paid tribute to his stable jockey, saying: "He's riding with confidence, they jump well. He's only 24, he's a fantastic team player and he's been so good for us. I'm really proud of him, he's done very well."
Rubaud is part-owned by Chris Giles whose brilliant season shows no sign of slowing down.
"It's my local track and I've been trying to win the Scottish Champion Hurdle for a few years, we've done it at last!" he said.
"Delighted. It's been a great season and it will hopefully continue on to Saturday at Sandown with Greaneteen."
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