Farmer, who has led Mind for the past 16 years, will join Age UK in October. He succeeds Steph Harland, who stepped down in September 2021 after three years in the role.
Mind said that during his time with the charity he had “worked with colleagues and partners to bring about dramatic changes in the mental health landscape, including a major shift in public awareness and attitudes”.
He also oversaw the launch of a new strategy and brand for the charity.
Farmer said it would be a “huge wrench” to leave the organisation, but he was a firm believer that there were times when a change of leader was important.
“It has been a huge honour to lead Mind and play a part in changing the conversations around mental health, securing significant changes for mental health and leading the Mind federation to new heights,” he said.
“Of course, there is much still to do to ensure that everybody with a mental health problem gets both the support and respect they are absolutely entitled to, and I will continue to be a massive supporter of the work Mind does.”
Stevie Spring, chair of Mind, said Farmer had been an outstanding leader.
Toby Strauss, chair of Age UK, said: “Paul brings with him a wealth of experience and expertise about mental health from his impressive tenure at Mind and his previous management roles at Rethink and Samaritans, and about the charity sector more generally.
“Paul’s commitment to the needs of older people makes him well placed to lead Age UK through the next stages of our journey, at a time when they have never been more pressing.”