Hughes takes reins for Rangers
The 48-year-old has succeeded Neil Warnock, who lost his job on Sunday night after Rangers slumped to within a point of the Premier League relegation zone.
Hughes appeared already to have been earmarked as Warnock's replacement, with the former Manchester City and Wales boss commencing formal talks with QPR on Monday.
Hughes quit Fulham at the end of last season after less than a year in charge, suggesting the club's ambitions did not match his own.
He therefore sought assurances on that front from QPR before agreeing to join the Championship winners, who were taken over earlier this season by Malaysian tycoon Tony Fernandes.
Reports suggest Fernandes is ready to bankroll a January recruitment drive which could see between £20million-£30million of new talent arrive at Loftus Road, with plans for a new 30,000-seater stadium also in the pipeline.
Hughes, who will take charge of first-team training this afternoon before being formally unveiled on Wednesday, told the club's official website: "It's a great feeling to be back in football and to be the manager of QPR.
"I'm fully aware of the challenge in the short and long term and I am genuinely excited about the ambition of the owners.
"Nobody can doubt the history of this great football club and the passion of its fantastically loyal supporters.
"Now the immediate priority is to consolidate our place in the Premier League, but beyond that, the future is very bright and fills me with great enthusiasm."
Chairman Fernandes said: "Mark has a proven track record in the Premier League, bringing a wealth of experience at both club and international level.
"He has a great passion to achieve as a manager and has already been hugely successful in his career.
"His ambitions match those of the board and we are delighted to have him at the helm."
Vice-chairman Amit Bhatia added: "Mark has a great managerial pedigree and has proven over the years to be a very astute manager.
"I am looking forward to working with him to bring success to the club."
Chief executive Philip Beard said: "Having spoken at length with Mark, I know he is brimming with enthusiasm and anticipation about the challenge of taking QPR forward and I believe he is the perfect choice to deliver the success we all desire."
Hughes, who had been linked with both Aston Villa and Sunderland since quitting Fulham, will be joined at QPR by assistant manager Mark Bowen, first-team coach Eddie Niedzwiecki and goalkeeping coach Kevin Hitchcock.
A raft of players have been linked with Rangers, including Didier Drogba, Alex, Christopher Samba, Nedum Onuoha, Darren Bent, Jermain Defoe, Wayne Bridge and Brazilian striker Henrique.
They have already seen a reported bid of between £1.5million and £2million rejected for Fulham forward Andy Johnson, who like Blackburn defender Samba has played under Hughes.
Hughes' first game in charge will be Sunday's trip to Newcastle, before which QPR could find themselves in the bottom three.
It was fear of immediate relegation to the Championship which prompted Fernandes to axe Warnock after a return of only two points from the last eight league matches and Saturday's FA Cup scare at MK Dons.
That was despite Warnock transforming the club's fortunes in his 22 months there, ending their 15-year exile from the Premier League in his first full season at the helm.
Prior to that, Rangers had 11 managers, including caretakers, in just over four years in what was one of the most turbulent periods in their history.
Fernandes' takeover in mid-August allowed 63-year-old Warnock to add a host of big names to his squad, but with mixed results.
Warnock has insisted he bears no grudges over his exit, but disputed the club's decision and was confident he would have kept them up.