His performances also earned him a place on this summer's British and Irish Lions tour to Australia.
He said: "I'm over the moon. It's been an unbelievable season for me and I'd like to thank all my team-mates at Leicester and the coaching staff who have helped me so much.
"Simon Hardy, my throwing coach, has been outstanding for me for the last three years.
"I knew I was up for the award, but to win it is fantastic. There are some great players and to win against them. I can't really put into words.
"Chris [Robshaw] won it last year and is a great bloke and a great mentor to learn from so it's great to follow in his footsteps."
He beat England scrum-half Danny Care, Gloucester back row Akapusi Qera, Wasps wing Christian Wade, Saracens second row Steve Borthwick and club-mate Julian Salvi to the award.