I'm not aware of a single catalogue that would encompass all early medieval manuscripts everywhere. Much more often, you'll find catalogues specific to individual libraries (or sometimes countries) that might be organized by period. You can also find catalogues of manuscripts relating to specific topics or places. (For instance, a quick search of "catalogue of manuscripts relating to" in my university's library gives me the Catalogue of Hebrew Manuscripts in the British Library and a catalogue of manuscripts in the Bodleian relating to Oxford as the top two results.)

For what it's worth, although it's true that the number of surviving manuscripts for early medieval Europe is comparatively small, you might be surprised at how many do survive. The Carolingians were fairly prolific producers of manuscripts, thanks to educational reforms, a push for religious orthodoxy, and even standardization of handwriting.

It would be incredibly difficult to catalogue all the early medieval manuscripts in a single list for a number of reasons. For one thing, they're spread out literally all over the world, sometimes in tiny libraries that few people are aware of. For another, dating manuscripts can be tricky -- would you include a manuscript you can date to your chosen period, plus or minus fifty years? A century? That's not to say that people haven't tried, but it's much easier and more effective to catalogue them in more discrete categories.

For the purposes of your question, there's a catalogue of Carolingian manuscripts compiled by Bernhard Bischoff (unfortunately in German, so it may or may not be of any use to you) that was published in 1998 as Katalog der festlaendischen Handschriften des neunten Jahrhunderts (Catalogue of continental manuscripts of the ninth century). You can also browse online repositories, although I just checked several and didn't find many early medieval manuscripts. E-Codices has four from the period you're interested in. Digital Scriptorium may have some, but they don't have a way to filter by date. Europeana has some later manuscripts, but their date filtering is also not great, so it can be tricky to browse for things if you don't know what you're looking for. All three of those websites are basically portals to other institutions' collections, so you can also go straight to institutions. The Bibliothèque nationale in Paris has an excellent digital collection. The English version of the page doesn't seem to be working right now, so here is a sample search of manuscripts in ascending order of date. The first page and a half or so are early medieval manuscripts, and they vary widely in subject matter - everything from gospels to theological tracts to medical treatises. Ireland also has a great website for manuscripts in the Irish language that includes some early medieval manuscripts. For instance, here's the Stowe Missal -- you can read the catalogue entry and look at each individual page of the manuscript.

If you're interested in other resources, I can definitely point you to some more -- there's a wide world of manuscript studies out there!