The 70-cap England international will take the reins when the Lions face the Black Ferns in a three-test series alongside pre-tour fixtures.
Yapp, currently Head of Women's Pathway at England Rugby, will take a sabbatical from her role to lead the tour. She will work part-time for the Lions from July before stepping into the position full-time from January.
"To lead the first-ever British & Irish Lions women's team is an incredible honour and something I'm immensely proud of," Yapp said in a statement.
"The Lions represents the very best of our sport, and this tour to New Zealand is an opportunity to create something truly special and help shape the future of women's rugby for years to come.
"I know from experience how challenging it is to face the Black Ferns on home soil, but that challenge is exactly what makes this tour so exciting."
Yapp brings impressive credentials to the role having represented England at three women's Rugby World Cups during her playing days before switching to coaching.
Her coaching resume spans club and international rugby, including stints as head coach of the England Under-20 women's team, Worcester Warriors Women and the Barbarians.
Most recently, she led the Australian national women's team at the 2025 Rugby World Cup, where they reached the quarter-finals.
"Jo's breadth of experience across the UK club game and the international women's game in the southern hemisphere made her an outstanding candidate for this role," said Ben Calveley, CEO of the British & Irish Lions.
"Her vision for bringing together players from the four Unions was hugely compelling and we are thrilled to welcome her on board."