The plea came from Sheila Drury, the new chair of ELWa - Education and Learning Wales, which funds post-16 education.
Speaking at the national conference for Welsh governors last week, she said: "We need to recognise that no one institution can necessarily deliver everything learners need and that collaborative working is a crucial way forward if we are to increase quality learning opportunities."
The former businesswoman, teacher and governor said there was a "moral case for ensuring that wasteful competition and duplication is eliminated."
The call for closer co-operation comes as the Welsh Assembly reviews the rules under which colleges have run themselves since they left local education authority control.
The rules allow colleges to compete for students, but it is expected that the Learning and Skills Council in England will reduce the overlap of courses and some duplication of administration has been reduced through college mergers.
Reducing duplication was one of the key reasons for creating ELWa and this has been achieved to some extent by colleges becoming centres of excellence and acting as a hub of expertise in certain subject areas.