More than 700 students will be taught at the new state-of-the-art Deeside Sixth building.
The £14.6m college is part of a major overhaul of post-16 education by Flintshire council.
First Minister Carwyn Jones will open the facility, based at Coleg Cambria's Deeside campus, on Friday.
In 2013, it was announced that sixth forms at Holywell, John Summers and Connah's Quay high schools were to be axed, with students instead moving to the new college.
A multi-million pound sixth form college centralising post-16 education in Flintshire has officially opened its doors.