The 43-year-old, famously known for partnering Imperial Commander to victory in the 2010 Cheltenham Gold Cup, started his career on the Flat in Ireland before landing the 2004-05 conditional jockeys' title.
Paddy Brennan, who landed the 2007 World Hurdle on fan-favourite Inglis Drever and the 2015 King George VI Chase on Cue Card, passed the 1500 winners mark with a memorable double at Catterick earlier in the season.
There wasn't to be a fairytale Cheltenham Festival victory for Paddy Brennan, but it was fitting the Galway-born rider, who enjoyed a career that spanned 27 years, would ride his final winner for trainer Fergal O'Brien.
Brennan rode 464 winners for the Gloucestershire-based handler in a relationship that blossomed in recent years.
The 9/1 chance arrived on the scene travelling powerfully and jumped the last with a five-length advantage. Both Moroder and Stumptown closed strongly up the Cheltenham hill, but the former could only get with a length and a half of the winner.
"In 27 years, I've been so, so lucky," said Brennan. "It has been a rollercoaster, so many ups and so many downs, but I feel I've got down to the edge of the ocean and walked down to the beach.
"I've been mulling it over for weeks and asked so many people's opinions if I was doing the right thing. I went for a coffee with my wife this morning and thought it's time for the next generation of jockeys.
"I am so pleased to have worked with the best in the game and I'm so proud of all the young lads in the weighing room. It's a tough gig.
"It was extra special to finish on a winner here today. I thought my ace card today was Kamsinas and if I didn't ride a winner today, I had a little chance tomorrow.
"When you drive past this place (Cheltenham Racecourse) to go shopping in Cheltenham it still gives you tingles even when it's empty as it is that kind of place. The people make it extra special but even when they are not here it is unique. When all the Irish come here for The Festival it is like home from home.
"I think I've left my mark in the weighing room with plenty of shouting as I'm a strict kind of lad, but I love them all.
"Being a jockey is 95 per cent disappointment and I've had 95 per cent disappointment for so many years. I've had some enjoyment but now I'm ready for the next chapter."
When questioned about what the next chapter would entail, Brennan added: "When I usually go on holiday you are thinking about your next ride, so I want a break from all that and I have a couple of things lined up. My phone number is there for anyone who wants to ring me and I'm ready for the future."
