he congratulated me ------ my success.

The correct preposition to use is: on.

Here's why:

• On is the most natural preposition to use with the verb "congratulated" when referring to someone's achievement. It indicates the specific reason for the congratulations.
• By suggesting a method or means of congratulating, like "by sending a card" or "by shaking my hand."
• At wouldn't be appropriate here. It's more commonly used for specific points in time.
• About can be used to talk generally about someone's success, but it's less specific than "on."

Therefore, "on" is the grammatically correct and most natural preposition to use in this context.