Turner, 33, retired at the end of last season but has agreed to be drafted in because of injuries to riders in the female side for racing’s annual team event on August 6.
The women’s team, representing teams from Great Britain and Ireland, Europe and the Rest of the World, beat the male riders’ team for the first time ever last year, but they have been rocked by injuries.
Turner, who was awarded an OBE in the Queen’s birthday honours list this month, will replace Australian star Michelle Payne, the Melbourne Cup winner who has been ruled out after suffering abdominal injuries in a recent fall.
The three-strong line-up will be completed by Canadian Emma-Jayne Wilson and Cathy Gannon, subject to her being fit following an injury.
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Turner said: “The Shergar Cup has always been my favourite day of the racing calendar and I wouldn’t have considered coming out of retirement for any other event.
“It’s a real shame that Michelle Payne is unable to join the team and I wish her a speedy recovery.
“I’m looking forward to the challenge and hope myself, Emma-Jayne and Cathy Gannon can recreate the magic of our team’s victory from last year.”
Turner rode professionally from 2000 until 2015, winning 761 races in Britain, where her many achievements included a champion apprentice title in 2005 (shared jointly with Saleem Golam), two Group 1 victories and a century of wins in a calendar year.
These were among a string of female firsts Turner accomplished in a spectacular career that also featured a top-tier success in America and wins for the Queen.