Residents near the site at 44 Sandhurst Road, Crowthorne, said the new building for the elderly would be too large, overlook their homes and cause noise, congestion and parking problems.
However, Bracknell Forest councillors said at a meeting on Thursday last week they could find no planning grounds to refuse the application by B&M Care.
The home would employ 50 full-time and 20 part-time staff.
Both Crowthorne and Wokingham Without parish councils opposed the bid, plus 15 residents wrote, objecting.
Tina McKenzie-Boyle, from Crowthorne Parish Council, spoke on behalf of residents during the planning committee meeting.
She said the new building would be "grossly over-bearing" and "over-look gardens and bedrooms". She said after the vote by a majority of the committee to approve planning permission: "It is very disappointing for the residents."
But at the meeting, Cllr Dale Birch said: "When I went searching for that golden bullet or silver bullet that would shoot this dead, I couldn't find it. I can't support refusal."
Committee chairman Cllr Colin Dudley added: "I tried desperately to look at good planning reasons to refuse this application and raise an alternative amendment but I really can't find them and there I'll also support this application." The existing large building on the site used to be staff accommodation for Wellington College but has been disused since 2007. It would be knocked down under the plans.
A previous application for a 75-bedroom care home of two and three storeys over a larger floorspace was turned down at appeal in February 2010, on grounds that it would affect the area's character and disturb residents.
The new application is for a Victorian-style red brick and tile building that is three storeys high facing Sandhurst Road but appearing three-and-a-half-storeys high at the back because of a lower ground floor level added due to the sloping site.
After the meeting, Emma Richards, from Goldsmith Way, Crowthorne, behind the site, said: "It's just going to be an absolute nightmare. It is so over-bearing."
There would be 32 car park spaces, with visitor parking accessed via Sandhurst Road and staff via Shaw Park. There would be an estimated 150 trips to or from the site a day.
Marcus Lambert, a planning consultant speaking on behalf of the applicant, told councillors the building would be a "considerable" distance from neighbouring properties and said: "All the boundaries are well screened and the flank sides of the care home it's proposed would have obscure glazed windows - I can't believe that the building would be overbearing."
Ian Sloan, from B&M Care, said they would listen to residents and work would probably start next year for the care home to open in 2014.