The Charles Byrne-trained 5-6 favourite jumped the last in front and ran on strongly for a four-and-a-half length success under jockey Davy Russell.
Donnas Palm was second and Sublimity third, with Celestial Halo, ridden by Ruby Walsh, finishing fourth.
Solwhit has been installed as favourite for the Smurfit Kappa Champion Hurdle at Cheltenham on 16 March.
Celestial Halo was the early leader but Sublimity led three fences from home, before Solwhit hit the front.
"He doesn't take much work, which after the weather we've had is a big help," said trainer Byrnes.
"But that's him today - take it or leave it, there's no improvement to come."
Winning jockey Russell added: "He travelled well into the straight, I was off the bridle before Sublimity but that's normal.
"He jumped accurately today and even idled before the line. He's lived up to our expectations.
"The hill at Cheltenham will be tailor-made for him, but that's only my opinion as I've never ridden a Champion Hurdle winner there before."