The tri-borough agreement between Hammersmith and Fulham, Kensington and Chelsea, and Westminster councils had been set up in 2012 to share resources in response to funding constraints.
But this finished in April after Kensington and Chelsea, and Westminster served notice to Hammersmith and Fulham, which they claimed was planning to leave the partnership.
During a focused visit to Hammersmith and Fulham in September, to check on care leaver support, inspectors noted the split but said that senior managers continue to be focused on providing good support for care leavers and improving their life chances.
They found that all care leavers, except for those in custody, are in suitable accommodation with a range of options on offer.
In addition, use of "Staying Put" arrangements, whereby young people can stay in foster care until they are 21, is increasing.
When housing problems arise support is deployed quickly, which means few care leavers are evicted, inspectors found. There was also found to be a focus on housing young people leaving care close to their neighbourhoods, with a high proportion living within the borough or a neighbouring council area.
"Care leavers in Hammersmith and Fulham receive effective support that helps many of them to achieve good outcomes, states an Ofsted letter to Hammersmith and Fulham Council.
"Since the last inspection in 2016, the local authority has disaggregated most social care services for children from the joint arrangements with Kensington and Chelsea, and Westminster, although some shared services remain.
"Senior managers continue to be clearly focused on sustaining and improving outcomes for care leavers and are aware of the areas where improvement is needed."
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Inspectors said they were particularly impressed with the effort social workers put into supporting care leavers and ensuring they stay in touch with them. They also found that the council is offering help beyond its statutory duties to make sure care leavers receive ongoing support.
"Highly skilled workers are persistent in engaging effectively with care leavers," states the letter.
"Staff make significant and tenacious efforts to stay in touch with young people leaving care.
"The local authority has been proactive in offering ongoing support to care leavers if necessary, even when there has been no statutory duty to do so.
"Social workers work hard to build rapport, and several young people reported positively about the quality of support and advice offered to them."
Areas of improvement include involving care leavers more in improving the service. Young people told inspectors that they are not formally consulted on how care leaver support should be developed.
Kensington and Chelsea and Westminster children's services continue to work together under a bi-borough agreement. Both were visited by Ofsted in the summer for a focused check on their "front door" support, which they found to be well run and backed by strong and committed leadership.
A spokesman for Hammersmith & Fulham Council said: "We're pleased with this inspection. It's the first time our care leavers' support has been assessed since becoming a sovereign service and this inspection report shows our commitment to delivering high quality services that meet the needs of all our residents.
"There are, of course, still elements to work on and we will use the inspection feedback to continue to develop the service and to apply the lessons across all our services."