The Birmingham-based trust’s four staff, who all work in fundraising and marketing, will transfer to Brain Tumour UK.
Jenny Baker, Brain Tumour UK’s chief executive, will remain chief executive.
Andy Foote, the trust’s founder, unpaid chief executive and chair, and two other trustees from his organisation, will join Brain Tumour UK’s board in June.
The trust’s offices in Solihull, west midlands, will be retained along with Brain Tumour UK’s headquarters in Chesham, Buckinghamshire.
Baker said the two organisations had different but complementary strengths. "Their complementary strength is fundraising and ours is patient support," she said. "We will be a greater force together."
The trust made losses of £21,027 in 2008/09 and £47,008 in 2009/10, but Foote said its income had tripled to about £750,000 in the last calendar year after it hired paid staff for the first time.
"We are in the strongest financial position we have ever been in, so finances were not a driver at all," he said.
"The problem is getting bigger. We need to do something different so we need a bigger voice with government and the public – joining with Brain Tumour UK gives us that."
Foote set up the charity in 2001 when his son, Joseph, was diagnosed with a brain tumour. Joseph died in 2007.