A record one in four university applicants received a "conditional unconditional" offer this year, figures from admissions service Ucas show.
But despite the rise in these offers, future degree students are now less likely to accept them, Ucas says.
Conditional unconditional offers give students a place - regardless of their A-level grades - on condition they make the university their firm first choice.
Critics say they encourage students not to work hard to get the best A-levels.
The latest Ucas figures show a quarter (25.1%) of 18-year-old university applicants from England, Northern Ireland and Wales - 64,825 students - received a conditional unconditional offer in 2019.
This is up 4.2 percentage points on 2018, from 20.9% (53,355 students).
Overall, among applicants holding five offers of places from universities, including one conditional unconditional offer, just over one in five (20.6%) chose to accept the conditional unconditional place.
This was down from 25.6% in 2014, Ucas said.
A breakdown by subject shows communications and media has the highest proportion of "conditional unconditional" offers (15.5%), followed by humanities and liberal arts (13.6%).
Ucas chief executive Clare Marchant said: "Students are considering their offers more carefully than ever, with the type of offer they receive having less of an impact than before.
"Our advice to students is to always think about what's most important for them when deciding which offers to accept.
"Unconditional offers remain a complex issue and our new insight will further inform the dialogue, forming a crucial contribution to the current admissions practice reviews.
"Their impact on attainment needs to be highlighted, though this must be seen alongside their role in widening participation activities and benefits to students' mental health."
Alistair Jarvis, chief executive of vice-chancellors' group Universities UK, said: "Universities UK continues its work through the 'fair admissions review' to consider the extent to which various university admissions practices are fair, transparent and operating in the best interests of students."
But Education Secretary Gavin Williamson has previously condemned the use of conditional unconditional offers, saying there is no place for them, and they can limit disadvantaged teenagers from going to the "very best academic institutions" possible.
The Association of School and College Leaders said these types of offers had "more to do with the frenetic scramble to put 'bums on seats' than the best interests of students."
General secretary Geoff Barton said: "It is good that students are now less likely to accept this type of unconditional offer than previously and suggests that young people are increasingly aware that the easy choice is not necessarily the best choice.
"But the students who are most vulnerable to this inducement are likely to be those who are less confident, and this will include young people from disadvantaged backgrounds for whom university is a daunting prospect.
"We need to make sure that these students in particular realise their full potential in all their qualifications and that they choose university courses which best suit their aptitudes and interests."