Chief executive of NCVYS Susanne Rauprich said initially the organisation's membership services and policy functions will merge into Ambition, and could be followed by other work programmes, subject to agreement from funders.
NCVYS will then close on 1 April. Ambition, which represents about 3,000 youth clubs and community projects, serving some 500,000 young people, will retain its current name.
The two organisations entered talks about a possible merger in mid-January. Prior to that, in October 2015, the organisations, along with UK Youth, had been in discussions about possible collaboration within the youth sector.
Susanne Rauprich said: "The process we have undertaken with Ambition was never just about the future of NCVYS but about the future of the youth sector in its widest sense.
“I hope what we have started here can be a platform for wider consolidation and collaboration, and for the support of all youth organisations in achieving a more united and resilient sector.
“This is not a time to focus on our individual organisations, but to look wide and wider still.”
Natalie Campbell, chair of NCVYS, added: “I’m delighted we have been able to secure a future for our membership, policy work and other services with Ambition, whom I know share our values and passion to work tirelessly in the best interests of the youth sector as a whole.”
The decision to merge the two organisations comes just 12 months after Ambition, which until July 2012 was known as Clubs for Young People, merged with the Confederation of Heads of Young People’s Services (Chyps), the organisation for leaders of local authority young people’s services.
At the end of January this year Ambition chief Helen Marshall announced she would be leaving Ambition in March to take up the chief executive post of youth sexual health charity Brook. Ambition is yet to announce a replacement.