Ofsted, which carried out a focused visit last month, reports that the service's leadership team has since last June "secured marked improvements in the local authority's response to contacts and referrals".
Serious problems in recruiting and retaining children's services staff had resulted in "excessive" workloads among some social workers, according to the joint targeted area inspection (JTAI) report published last summer.
The service, which is rated "requires improvement", has cut the children's social worker vacancy rate from 37 per cent to 25 per cent, with empty positions filled by agency staff. Ofsted describes social workers as "positive and optimistic".
Latest DfE workforce statistics show that the average vacancy rate in the South East as of 30 September last year, was 14 per cent, and the national average was 15 per cent.
The letter, addressed to director of children and adults' services Ian Sutherland, states: "Processes to support social work practice, new at the time of the previous visit, have been embedded and strengthened.
"In most cases, children and their families now receive a timely and proportionate response to their needs.
"The progress that has been achieved has been sustained, despite a significant increase in the number of contacts and referrals."
Last year's JTAI, which looked in detail at the multi-agency safeguarding hub (Mash) response to domestic abuse, flagged that decision-making over children in long-standing situations of concern "is inconsistent because it is not always well matched to risk".
In the more recent report, Ofsted praises a "welcome increase" in the range of multi-agency professionals who are based in, or linked to, Mash.
This includes recent appointments of an education lead, a domestic abuse officer and a missing and exploitation co-ordinator.
It adds: "Mash outcome meetings, held twice daily, are effective and facilitate good information sharing and discussion.
"This encourages appropriate challenge and professional curiosity, informing timely decision-making and recommendations that are matched well to risk and need.
"When children are at immediate risk of significant harm, this is quickly recognised, and referrals are progressed to child protection strategy meetings and assessment teams, so that protective action can be taken.
"Strategy meetings, although not always informed by the presence of, or full information from, all relevant agencies, are held promptly and lead to appropriate decisions about threshold and next steps.
"The full-time deployment of a police sergeant in the Mash to participate in strategy discussions has been positive."
Inspectors noted progress with the overall engagement of the police, but some domestic abuse notifications to the single point of access remain of concern.
Delays of between four days, and in one case four weeks, are highlighted.
It adds: "Although no children were found to have suffered further harm as a result, these delays potentially leave children in situations of unassessed risk."
Inspectors note that "suitable plans are in place" to address weaknesses, such as with the quality of assessments.
Last year Medway opened four children and family hubs and 11 wellbeing centres, recognised by Ofsted as a "sound base for the provision of early help services in Medway".
Councillor Andrew Mackness, Medway's portfolio holder for children's services, said: "We will continue to work even closer with health partners and we are working to address the quality of assessments and timeliness of visits to children and their families as quickly as possible.
"We have appointed new permanent staff to help reduce caseloads and ensure we continue to provide each child and family with the help and support they deserve."