An estimated 10,135,618 lives have been lost since the 1967 Abortion Act came into effect, according to the Right to Life UK group.
The figure, covering England, Wales and Scotland, was released on Thursday to coincide with the 55th anniversary of the Abortion Act coming into effect in 1968, six months after it received Royal Assent.
Right to Life UK said the numbers were a "national tragedy" as it called on people to do more to defend the rights of the unborn.
Spokesperson for Right To Life UK, Catherine Robinson said: "The UK's abortion law is failing both women and unborn babies.
"It is a national tragedy that 10,135,618 lives have been lost since the 1967 Abortion Act came into effect, each one a unique and valuable human being who was denied the right to life.
"Every one of these abortions represents a collective failure of our society to protect the lives of babies in the womb and a failure to offer full support to women with unplanned pregnancies.
"While we may pause to commemorate this tragedy, this day also serves as a call to action for people around the country to renew their efforts to do everything they can to help ensure more lives are saved from abortion in the future."
Data from the Department of Health and Social Care revealed that there were a record 214,869 abortions in England and Wales in 2021, an increase of 4,009 abortions from 2020.
A further 13,758 terminations took place in Scotland in the same year.
The rise coincided with the first full year of abortion 'pills by post' in England and Wales. The service was introduced during the pandemic to allow women and girls to receive abortion pills in the post from abortion providers after an e-consultation.
In light of the increasing numbers of abortions, Right to Life UK is asking people to consider volunteering with pregnancy support centres or other pro-life initiatives, and contact their MPs to encourage them to support protections for unborn babies and their mothers.
"By being proactive and taking action, every single one of us can be part of building a pro-life nation where we protect and defend the right to life of every human being from conception to natural death," Ms Robinson added.
