Pupils should be able to apply for university places only after they receive their A-level results, the lecturers' union has said.
A report by the University and College Union said the change could mean the end of unconditional offers and the "chaotic" clearing system.
Admissions body Ucas said the proposals "appeal" but would be hard to bring in.
Most UK school leavers currently apply for courses months before their exams, with offers based on predicted results.
In 2018 nearly a quarter of university applicants in England, Wales and Northern Ireland (67,915) received an unconditional offer - up from 1% (2,985) in 2013 - Ucas figures show.
The UCU report says there is anecdotal evidence this shows a "marketised approach to increasing student recruitment".
Its study, A Post-qualification Application: A Student-centred Model For Higher Education Admissions In England, Northern Ireland And Wales, also suggests delaying when first-year courses begin to November in order to help students prepare.
"Such a move would not only be fairer for students, it would bring the UK into line with the rest of the world and eliminate the use of controversial unconditional offers and the chaotic clearing process," said the union's head of policy Matt Waddup.
Clearing is the system that matches students who did not get the grades they needed (and those who turned their offers down or did not get any) to courses with vacancies.
The UCU is calling on the government to commission an independent review of university admissions.
But Ucas chief executive Clare Marchant said a UK-wide consultation carried out in 2012 found waiting for students' results would be likely to "significantly disadvantage" disabled students unless secondary or university calendars also change.
"Young people need the support of their teachers when making application choices, and this isn't readily available to all when schools and colleges are closed during August," Ms Marchant said.
"Once students have a place, they need time to find accommodation, finalise their access to financial support, and to prepare for their studies.
"Universities and colleges need time for interviews, auditions and considering contextual information about applicants, and time to put in place support services to help care leavers, first in family, and disabled students, transition into higher education."