Staffordshire ambulance chiefs have formally agreed to merge with the West Midlands service.
The move still needs to be ratified by the strategic health authority and the government, but both are expected to be a formality.
Both ambulance services were told by the government last year that they must merge at a time to be agreed locally.
The merger, which sparked a 5,000 signature petition in protest, is expected to take place on 1 October.
Staffordshire Ambulance Trust did not join the West Midlands service when it was created in 2006 amid fears that it would damage its response times.
Response time targets
The West Midlands organisation was formed when the Hereford and Worcester, Coventry and Warwickshire, West Midlands trusts, which also covered Shropshire, merged last year.
The government had set both trusts certain targets before the merger could be approved.
These included responding to 75% of life-threatening incidents within eight minutes and 95% within 19 minutes.
They also had to demonstrate clinical performance for heart attack patients, good sickness absence levels among staff and sound finances.
Staffordshire Ambulance Service Chairman Robert Lake said: "I recommended that my board approve the merger timetable for a number of reasons.
"It is clear that the two trusts are operating at a similar level of performance and are now the top two performing services in the country in terms of response targets.
"Where there are areas of difference the gap is closing rapidly and there are action plans in place to ensure that change continues.
"The West Midlands has introduced working practices that have proven successful in Staffordshire and vice versa. It is a two way process."