Speaking at the Labour party conference in Liverpool, Rayner will say that Labour must ensure that children's life chances are not impacted by a lack of support.
The taskforce will be chaired by Liz Snape, deputy general secretary of Unison. She will work alongside Labour's shadow education team and childcare experts.
Rayner, who was appointed shadow education secretary in July, following the resignation of Pat Glass, is expected to tell delegates that Sure Start centres helped her to improve her prospects.
"I left school at 16, pregnant, with no qualifications," Rayner will say.
"Some may argue I was not a great role model for today's young people. The direction of my life was set but something happened.
"Labour's Sure Start centres gave me and my friends, and our children, the help and support we needed to grow and develop. They changed the lives of three million children and their parents.
"The Tories have now closed more than 800 Sure Start centres, and more to come. Shutting the door in the faces of our children and their parents."
Rayner will add that she wants her party to aim to provide care and support for every child to fulfil their potential, and to help parents back to work.
"Conference, unlike the Tories, Labour will never turn our backs on our children and their families; never put political dogma before the ambition of every parent to do the very best for their child," she will say.
"Because excellent childcare changes lives for the better, as it did for my eldest son, for my two youngest boys, and for me."
Neil Leitch, chief executive of the Pre-school Learning Alliance, said:
"At a time of such significant change for the sector, a widening of the debate around early education, and the policies needed to sustain quality provision, can only be a positive thing.
"In the run-up to the last election, political parties on all sides made promises to parents on childcare that weren't necessarily feasible, sustainable or, crucially, in the best interests of children. This approach must change.
"We hope that the new taskforce will work with the sector to ensure that any early years policies developed by Labour are directly informed by those working on the frontline, and have the needs of the child at their core."