It’ll be Barney behind the bar on Long Island!

Actor Neil Patrick Harris will be serving up drinks Sunday at Sunset Harbor in East Hampton.

Best known for “How I Met Your Mother” and “Doogie Howser, M.D.,” the multi-time Emmy winner will be in Suffolk as part of a special promotion with a company that makes ready-to-drink cocktails.

Harris will be mixing up an espresso martini known as “The After Hours.”

He will be behind the bar tonight from 5:30 to 6:30 p.m.