Alcaraz blasted 33 winners and 18 aces to subdue the gritty Czech world number 30 in two hours and 10 minutes in west London.
The Spaniard has now won five trophies this year, adding to his titles on clay at the French Open, Rome and Monte Carlo, as well as the hard courts of Rotterdam.
“I’m happy to lift this trophy once again. It’s a nightmare to play against Jiri, but it’s been an incredible week,” Alcaraz said.
“I came without expectations. I just wanted to play good tennis and get used to the grass, ” he added. “It’s really special playing here every year. I can’t wait to come back next year.”
For a player raised on the clay courts of Spain, Alcaraz has developed into a formidable force on grass as he starts his bid for a third successive Wimbledon title on June 30.
In contrast, Lehecka was playing in his first grass-court final after a shock win against British star Jack Draper in the last four.
The 23-year-old was the first Czech in the Queen’s final since Ivan Lendl in 1990. (AFP)