Henderson, who came through the youth ranks at the club, has been a fixture in the first-team squad after spending part of last term on loan at Coventry City.
Meyler joined the Black Cats from Cork City in 2008 and has made 10 appearances for Steve Bruce's side since making his debut in December.
Bruce revealed last week that the pair were close to signing new deals and the Sunderland boss is delighted Henderson and Meyler are tied down until 2015.
"I've been delighted with the way Jordan and David have applied themselves since I arrived at the club and credit has to go to the Academy staff for the fantastic work they do with our young players," Bruce told the club's official website.
"You look for players to step up to the plate and make an impression when you first arrive and over the course of the last nine months they've grasped the opportunity with both hands.
"It blazes a trail for the younger players at the club who can see there is a route into the first team if they apply themselves like Jordan and David have.
"We're delighted to have secured their services for another five years."