Glamis Hall hosted a lunch club, including a three-course meal and activities, at its Wellingborough home.
The hall was transferred to the control of community group Glamis Hall for All at the end of last year.
Wellingborough Borough Council had planned to close it saying the hall was "no longer fit for purpose".
Graham Campbell, whose father had been going to Glamis Hall for 20 years since he suffered a stroke, called the re-opening "just brilliant".
He said: "The people we have spoken to are so pleased. That is what makes it all worthwhile."
About 180 people use the hall's facilities regularly, but the borough council decided in June that the 40-year-old building was no longer fit for purpose and needed extensive refurbishment.
It was deemed too expensive to run and had been supported using discretionary funding that was no longer available.
The council decided to close Glamis Hall at the end of the year sparking a protests from users, their carers and community groups.
Glamis Hall for All was set up in response and raised a 10,000-signature petition to save the centre.
Freehold of the building was granted to the group after it presented a business plan to run it as a community amenity.
The borough council also confirmed the group would be given a one-off capital grant of up to Â£250,000 to help repair and refurbish the building.
Mr Campbell said the group would need plenty of volunteers and would have to apply for more funding.
He said: "We can work on that. No-one thought we would get that far."
A day centre for older people which had been threatened with closure has opened for the first time under the control of the group which saved it.