Halewood Academy in Knowsley said its sixth form is not financially viable and will be closed by August next year.
About 900 people studied A-levels outside of the borough last year.
Knowsley Council met with local MPs and schools minister Nick Gibb and have pledged to ensure A-levels are taught.
They agreed to hold regular meetings to "ensure good A-level provision" by September 2017.
Council members in charge of children's services, Gary See and Paul Boyce, met with the schools minister, local MPs and the regional schools commissioner on Tuesday.
Mr See said 900 young people from Knowsley studied A-levels outside of the borough last year so they are "therefore confident" they will be able to "create a new offer that provides our young people with a choice".
Knowsley has the lowest proportion of students taking A-levels in England at 2%.
Following a consultation process, Halewood Academy's governors have submitted a business case to the Secretary of State for Education, Nicky Morgan, who is yet to make the final decision on the closure.
Education chiefs at a borough under-threat of becoming a "no A-level" area are determined the qualifications will continue despite the planned closure of the only sixth form offering them.