Champion jockey for the last 18 seasons, the 39-year-old Irishman broke into a broad smile after driving 6-4 favourite Mountain Tunes to a narrow victory at Towcester racecourse in the English shires.
Aptly, the success came for trainer Jonjo O'Neill and owner JP McManus, with whom McCoy has enjoyed so much success in the Irishman's green and yellow striped silks.
"It's amazing, it couldn't have worked out any better for Jonjo, JP - the McManus's have been so good to me, it was always going to be hopefully that I was going to ride it in JP's colours," McCoy told At The Races television.
McManus was there to greet his jockey and told reporters: "What a man and what a ride. I think he was more pleased because when he came in he said it was a nice horse!"
Surrounded by weighing-room colleagues, McCoy was showered with champagne and joined in the winners' enclosure by his wife Chanelle and two young children, with five-year-old daughter Eve afforded the day off school.
McCoy's 4,000 winners have come from 16,152 rides - a strike rate of 24.8 percent - and his feat in reaching the landmark can be put in perspective with Richard Johnson, the next most successful jump jockey, on 2,567.
Johnson, 15-times a runner-up to McCoy in the jockeys' championship, was one of many to pay tribute.
"What he's achieved has been amazing," he said. "He has completely rewritten what we thought was achievable in a season, and a career.
"He rarely makes mistakes - you would struggle to think of one. He is a machine who turns out winners."
McCoy has broken record after record in his relentless pursuit of winners since his first success as a 17-year-old in Ireland in 1992.
Helped by a flourishing partnership with trainer Martin Pipe, who churned out a seemingly endless supply of winners over jumps from his Somerset base, McCoy never looked back after riding his first winner in England in 1994.
He became the fastest jockey to 200 winners in a season in 1998 and the quickest to 1,000 career wins, taking just over five years.
In 2002 he broke the 55-year-old record of Gordon Richards for most winners in a season and went on to claim 289 winners that season.
His big-race wins include two Cheltenham Gold Cups - on Mr Mulligan in 1997 and Synchronised last year - three Champion Hurdles, and after 15 failed attempts, an emotional first Grand National victory at Aintree came his way in 2010 when he rode O'Neill and McManus's Don't Push It to victory.
His 4,000th win also coincided with the publication on Thursday of McCoy's first novel "Taking The Fall", a racing thriller.
As well as the highs, McCoy has had his fair share of body-shuddering lows. Jump jockeys risk serious injury every time they climb into the saddle and McCoy's list is long and painful.
He has broken middle and lower vertebrae, both shoulder blades, both collar bones, ribs, ankle, cheekbones, wrist and leg.
Dozens of figures from both horseracing and other sports have paid tribute to McCoy:
Mick Fitzgerald, ex professional jockey and now Channel 4 Racing presenter: “It is a huge deal, we’ll never see anything like it again. To have achieved this amount of winners in such as short space of time tells its own story and I’d like to offer him my sincere congratulations.”
Clare Balding, television presenter: “AP isn’t just the greatest jockey I have ever seen, he is the greatest sportsman I have ever come across. Bearing in mind he has been Champion Jockey for 18 consecutive years and Champion Conditional Jockey before that, he has never not been champion in his career. He has transcended the world of Jump racing and that, for me, is why he is an outstanding all round sportsmen. I feel very fortunate to have watched him throughout his career and that he chose racing. It’s hard to sum up how much admiration I have for him, he is an extraordinary human-being and amazingly kind. He is the Champion, has been from day one and will be until the day he finishes - he’ll be the best ever. It’s a privilege to know him.”
Michael Owen, ex-England footballer and horseracing fanatic: “He’s a phenomenon. To get to the top of your sport is hard enough but to stay there and to stay there for as long as AP has is quite astounding. And to do so in a sport that’s very hard mentally and physically – he must have broken every bone in his body and to have done it for so many years is it’s just an outstanding achievement. He’s an outstanding person and professional and a great ambassador for the sport. To reach 4000 winners is a phenomenal achievement and surely no one will do that again.”
Rod Street, Chief Executive of Great British Racing: “After all he’s achieved in racing, AP was already a legend and this latest incredible achievement just confirms his position amongst sport’s pantheon of greats. If you were going imagine the perfect ambassador for the sport, you would, only in your wildest dreams, dare to come up with AP – a man whose incredible talent is matched only by his unrelenting will to win and his phenomenal mental and physical toughness. He is the ultimate sportsman but also just an incredibly nice, funny and modest bloke. As a sport, we are incredibly lucky to have him.”
Richard Johnson, only the second jump jockey after McCoy to have ridden 2,500 winners: "What he's achieved has been amazing. He has completely rewritten what we thought was achievable in a season, and a career. Whether it's a Monday, a Saturday or a Festival, he's hungry and consistent every day. He rarely makes mistakes - you would struggle to think of one. He is a machine who turns out winners. He seems to get it right all the time and is a great ambassador for our sport, a true professional sportsman.”
Nick Scholfield, young professional jump jockey: “AP McCoy is absolutely remarkable. I’ve ridden 300 winners, and to imagine getting to 4,000 is something that really puts it in to perspective. You have to have dreams, and mine would be to ride that many winners, but he has set the bar so high that it’s unlikely that any jockey will ever achieve it again. What makes AP all the more remarkable is that he is riding as well today as he was when he first started in the 1990s. He just hasn’t deteriorated at all with age, although it would be great if he did as it would give the rest of us a chance!”
Paul Bittar, Chief Executive of the British Horseracing Authority: "It is nothing short of an astonishing achievement for AP McCoy to reach 4,000 winners in a sport which he has dominated for 18 years. He possesses the best qualities a modern day sportsman can aspire to – he is driven purely by a burning desire to win and to exceed the incredibly high standards he sets himself. His quest for success as a rider is his defining characteristic and the remarkable esteem in which he is held by his fellow jockeys and all within the sport is testament to that. To have ridden 4,000 winners is another incredible landmark in a glittering career, adding to those which already set him apart. British Racing is incredibly fortunate to have been blessed with a sportsman of the calibre of AP McCoy."
Paul Struthers, Chief Executive of the Professional Jockeys Association: "On the track AP is simply unbelievable. Unbelievably talented; unbelievably determined; unbelievably competitive and unbelievably tough. However, as driven and committed as he is on the track, he recognises that with success comes responsibility. He is Joint-President of the Professional Jockeys Association and is a strong supporter of PJA schemes that benefit all jockeys equally yet the busiest and most successful jockeys pay more for. He is also a passionate supporter of the Injured Jockeys Fund and is always happy to give up his spare time to help them in any way he can. You can have nothing but the utmost respect and admiration for AP. Everyone at the PJA congratulates him on this truly remarkable achievement. He's one of the most remarkable sportsmen we've ever seen in the United Kingdom and racing will never see anything like it again."