The pair, who guided the Cherries to promotion from League One last season, will now remain at Dean Court until June 2018.
Chief executive Neill Blake told the club's official website: "I'm absolutely delighted to have secured the services of Eddie and Jason for a further two seasons.
"Maxim [Demin] and I were always keen to show our faith in the pair, and an extension to their existing deals seems like the perfect way to do this.
"Eddie and Jason have quickly become the most successful management team in the club's history and it is imperative that we continue our journey with them at the helm."
Howe was reappointed Bournemouth boss in October 2012, having previously managed the club between 2009 and 2011.