Like Hughes, fellow left-handed batsman Khawaja lost his place in the Test team last summer and along with off-spinner Hauritz hope to break back into the Australian side via the Bulls rather than the Blues.
It is a tremendous coup for Queensland coach and ex-Test batsman Darren Lehmann but the loss of three players in quick succession may raise eyebrows about the state of NSW cricket.
However, Khawaja was only complimentary of NSW in a statement released on Friday by the Bulls trumpeting their major signings.
"The decision to join Queensland has been the toughest decision of my career, particularly because I had to leave my home, my mates, my family, and my clubs of Cricket NSW and Randwick Petersham," he said.
"I owe a great deal to where I am, and what I've achieved, to Cricket NSW and the 'Randy-Petes'.
"I would like to thank David Thompson, all the coaching and office staff, and all the players who've given me some great memories and even greater lessons about cricket.
"And to Bill Anderson and Mike Whitney for all they have done in what is one of the best run clubs in Australia.
"I'm extremely excited about joining Queensland and taking my cricket to the next level. I have a big role and it's a perfect environment for me to grow as a player and a person."
Khawaja, 25, has played six Tests scoring 263 runs at 29.22 but has been overtaken in the pecking order by the likes of Peter Forrest who will now be his new Queensland teammate.
Forrest also left NSW for Queensland with spectacular results, breaking into the Australian squad last season and making his one-day international debut.
Hauritz, 30, made his first class debut for Queensland a decade ago before linking with NSW in 2006-07.
He has played 17 Tests with 63 wickets at 34.98, 58 ODIs (63 wickets at 34.15) and three T20 internationals (two at 23.50).
Hauritz - who last played Test cricket in 2010 - will start pre-season training with the Bulls next week while Khawaja is currently playing for Derbyshire in England and is expected to link with Queensland in September.