Cowell, 53, who is expecting his first child with girlfriend Lauren Silverman, recently saw a scan of his baby, reported Daily Mirror.
"It is just surreal. You literally see this thing which is now alive moving around. I feel very paternal right now. So I am very happy," he said.
Cowell previously said that he was not interested in having kids.
"I can assure you: I won't go soft," he said.
Cowell and Lauren, who was married to former husband Andrew Silverman when news of her pregnancy broke in July, recently vacationed together in the South of France, where they were spotted holding hands while strolling the beach.