The first Diplomas will be taught in schools and colleges from September
The university admissions service says more than 100 higher education institutions have now provided statements backing the new Diplomas.
Ucas asked its 309 member institutions to publish their views so students know which are likely to accept them.
The Diplomas are industry-based qualifications being introduced in England's schools and colleges.
Concerns have been raised that some universities will not consider them in the same light as A-levels or Highers.
Ucas chief executive Anthony McClaran said: "It is very encouraging that a wide cross section of universities and colleges have positively indicated that they view the Advanced Diplomas as a suitable entry route into higher education.
"These statements go a long way to placing the Advanced Diplomas firmly in the spectrum of qualifications that universities consider provide students with the breadth of skills and knowledge that they will need to be successful at the higher education level."
Ucas's intervention comes as ministers are expected to announce that the take-up of Diplomas for this autumn is far lower than had been hoped for.
The individual institutions' statements are published on the Ucas website.
They include some of the most prestigious research universities belonging to the Russell Group.
A statement from the group, released last October, had particularly welcomed the introduction of a science diploma because of its concern about the low proportion of students - largely from state schools - taking science A-levels.
But it added: "However, we are concerned to ensure that the diploma sufficiently equips candidates with the skills and knowledge they need to flourish on our courses."
The University of Birmingham, a member of the group, says in its own statement to Ucas: "We encourage applications from those offering new Diplomas.
"Diploma candidates should consult the admissions office to check that their Diploma is suitable for their chosen programme."
Some statements are less "supporting" than others.
Cambridge university, for example, says: "We will be considering the acceptability of the new Diplomas for our courses on a case-by-case basis as details of the specialised learning options within each Advanced Diploma are confirmed."
Of the first phase of Diplomas the only potentially acceptable one cited by Cambridge is advanced engineering - "subject to students having taken appropriate options within their specialised learning".
Most though are more welcoming, albeit with caveats.
The University of Reading, for example, says: "The university considers the Advanced (Level 3) Diplomas as being an equivalent level qualification to A-levels and therefore satisfying the general entrance requirements for entry to an undergraduate programme.
"Specific requirements will depend on the exact programme applied for. Specific additional/specialised learning may be required."