No, not on its own. A merchant account with bad credit is harder to place than one with a clean file, but a poor score is a factor an underwriter weighs, not a veto it applies.
The reason comes down to what the processor is actually deciding. A bank reading your credit is asking whether you will repay a loan. A processor is asking a narrower question. Will your card sales hold up without draining its money in disputes six months from now?
Your credit informs that second question. It does not answer it. A five-year-old discharged bankruptcy sitting next to twelve months of clean processing reads nothing like a fresh default on a business with no history at all.
This is also where mainstream platforms and high-risk specialists part company. Stripe, Square, and PayPal run credit and category as a fast pass-or-fail screen, which is why so many owners get declined by an automated system they cannot appeal to. A specialist underwrites the file instead of filtering it, which means there is a conversation to have and context that can be read.
The practical version is this. We approve virtually every legitimate merchant, and a weak score on its own is not the thing that makes a file illegitimate. What changes with bad credit is the shape of the offer, not usually the answer. Expect a reserve, a lower starting volume cap, or both, and expect the underwriter to lean harder on evidence you can supply.
For the underwriting mechanics in depth, including what the FICO bands mean and how a bankruptcy ages off, see how to get a merchant account with bad credit. This page is about getting placed.