The care group is taking over Oakland nursing home, on White Point Road, securing the care of its 13 residents and the jobs of its 25 staff.
The home on the West Cliff is to be renamed - and the company is looking for suggestions that will signal a fresh start for it.
All existing Oakland staff are being offered posts with Saint Cecilia’s, matching their current pay, terms, and conditions.
Saint Cecilia’s Managing Director Mike Padgham said: “We are delighted to complete the takeover of Oakland and look forward to now welcoming the home, its residents, and staff to the Saint Cecilia’s family.
“Following successful negotiations, we are pleased that this popular nursing home has been retained for the Whitby community.
“The staff have done an amazing job ensuring continuity of care at the home during a very uncertain period and we will now be working with them and with the residents and their families to take the home on to a bright new future.
“We decided on a name change to signal a fresh start for the home and we are open to suggestions.
"If someone comes up with a new and inspirational name for the home, we will give a donation to a charity of their choice.
“We are grateful for the support of North Yorkshire County Council, the Care Quality Commission and North Yorkshire Clinical Commissioning Group during this transfer.”
Saint Cecilia’s has appointed Tom Johnstone as interim manager and has begun recruiting other new staff for the home.
It is looking for applicants for a number of posts.
Dale Owens, Assistant Director of Service Development and Prevention at North Yorkshire County Council, said: “We know the importance of Oakland Nursing Home to the community and are very pleased to see it move on to a new phase.
"North Yorkshire worked hard to help achieve that result.
“Our priority was to ensure its residents get the best possible care and the peace of mind of knowing it has a secure future.
"This development also provides job security to the staff and we look forward to working with the new team.”
The home becomes Saint Cecilia’s second nursing home, joining Saint Cecilia’s Nursing Home on Queen Margaret’s Road in Scarborough.
Mr Padgham said although it was a challenging time for social care, he believed the sector had "a very positive and bright future".
“The addition of Oakland helps us to grow and strengthen the company to enable us to keep providing that care and also to provide greater opportunities for progression across the group for our staff," he added.