No, using Credit Karma does not lower your credit score. When Credit Karma retrieves your credit score, we do so by requesting your credit information on your behalf. This is known as a soft inquiry, and these types of inquiries aren’t shown to creditors. They don’t affect your credit at all.
The kind of inquiries that influence your credit score are called hard inquiries, which are typically placed on your report when you apply for a new line of credit.