Howard Sinclair, chief executive of Broadway, will lead the merged organisation under the Broadway name.
He said the catalyst for the merger had been the economic situation of both organisations, but that it also made sense to merge the charities’ advice services because they would be stronger together.
Broadway has 225 employees and Threshold has 20, said Sinclair. He said there would be no redundancies at either charity because of the merger, but some Threshold staff could face redundancy because it had been given notice on two contracts.
Sinclair said neither charities’ services would be affected. They will be run from Broadway’s offices, which are spread across the capital, he said.
He said he hoped that Graham Slater, chief executive of Threshold, would join the organisation to lead its advice services.
Slater was unavailable for comment but said in a statement: "Threshold took a strategic decision some time ago to look for merger with a suitable partner as the best way to safeguard and grow our services. Broadway and Threshold have similar client groups, complementary services and a similar ethos."