You will have to send a new connection request. At that moment, they will likely realize there was a gap in the connection history. While they won't see a "block" log, they will see a fresh request from someone they swear they used to be connected to—which is its own awkward conversation. You can block someone on LinkedIn with the confidence that you won't trigger a humiliating alert. LinkedIn handles the block with the same silent treatment as most other social networks (like Instagram or X).

However, the practical answer is more nuanced. While the platform prioritizes discretion, a savvy user will likely figure it out on their own.

You consider the "Block" button. But a nagging question stops you: If I block someone on LinkedIn, will they know?

But to answer your original question: Will they know?