The Italian jockey rode nine English Classic winners for Godolphin and partnered the great Dubai Millennium to glory in the Dubai World Cup of 2000, one of his three wins in the world’s richest race.
Dettori, who rode Godolphin’s first Classic winner, Balanchine, in 1994 and has been associated with many of the stable’s top horses since then, said: “I have had 18 wonderful years.
“Godolphin has been a major part of everything I have achieved in racing and I have loved every minute of it.
“I feel the time has come for a change. My position in the stable has changed a little bit and I need a new challenge.
“Sheikh Mohammed has been an unbelievable boss to me. He had the confidence to take me on board when I was young and we smashed every record together. I will be forever grateful to him for everything he has done for me and for my family.”
Dettori, who earlier this month teamed up with the Coolmore operation to ride Aidan O’Brien’s Camelot in the Prix de l’Arc de Triomphe, has been sharing the Godolphin rides with fellow retained riders Mickael Barzalona and Silvestre de Sousa, who will continue in their roles in 2013.
Barzalona rode Encke to victory for Godolphin in the Ladbrokes St Leger at Doncaster in September when Dettori picked up a spare ride on Michelangelo for trainer John Gosden.
A host of Dettori’s big-race winners have been trained by Saeed bin Suroor, including four of those that formed the rider’s ’Magnificent Seven’ at Ascot on September 28, 1996.
The pair were in Milan yesterday where Dettori steered Retrieve into second place in the Group One Gran Premio Del Jockey Club Italiano at San Siro.
Speaking from Milan, where he was supervising Godolphin’s runner, Bin Suroor said: “We have been good friends and have travelled all over the world and have had great times.
“We have been like brothers. I have seen him every morning and sometimes we come back after midnight from racing.
“He has done a great job for Godolphin. It is sad but at the same time I wish him good luck.
“He is the best jockey in the world and I am sure he will do well also in the future.”
Dettori, winner of 110 Group or Grade One races in the royal blue silks, thanked the many Godolphin staff who had helped him to achieve the success he has enjoyed with the stable.
“The whole team have been fantastic – none of it would have been possible without them,” he said.