Having a Credit Karma account will not directly lower your credit scores.
We request your credit report information on your behalf from TransUnion and Equifax. This is known as a soft inquiry, which won’t impact your scores.
On the other hand, hard inquiries can influence your credit scores. These are typically placed on your credit reports when you apply for a new line of credit, regardless if your application was approved or not. So if you apply for a credit card or loan through Credit Karma or elsewhere, you will receive a hard inquiry, which can affect your credit scores.
Here’s more information about the differences between hard and soft inquiries.