Cllr Julie Howell, who represents the Orton Waterville ward, has been group leader for three years, but has stepped down from the role.
On Thursday’s council elections, cllr Howell secured more votes than any other candidate in Peterborough.
While she has stepped down as group leader – and will now be group secretary – cllr Howell will continue to be a ward councillor.
Former deputy leader Cllr Nicola Day will be the new Green Party leader, while cllr Kirsty Knight will be deputy leader. Both also represent the Orton Waterville ward.
Cllr Howell said: “I’ve been group leader for the past three years, but decided not to put myself forward for the role this year to give another member of the team the opportunity.
"I wish Cllr Day the very best in this role. I’m sure she’ll be terrific.”