ORCHARD PARK, NY - The Buffalo Bills have made it official.

Free agent Mario Williams has signed a multi-million dollar deal with the Buffalo Bills.

"You don't get many chances and opportunities like this to be the guy who can help the team get over the hump and that is definitely what I am here for," Williams told the media at his introductory press conference.

Bills CEO Russ Brandontweeted a picture of Williams signing his contract Thursday at Ralph Wilson Stadium.

The Bills' courtship of DE-OLB Mario Williams has paid off -- for both parties.

With 53 career sacks, OLB Mario Williams is the Texans' career leader in the category.

"We've said from day one that if there's a guy there that we think can make the difference we'll be aggressive and go after the guy," said Bills GM Buddy Nix. "So this just plugs up a piece of the puzzle and he'll get us over the hump."

The former Texans pass rusher, the most coveted defensive player on the free agent market, signed a six-year deal in Buffalo worth up to $100 million with $50 million guaranteed -- the richest haul ever for an NFL defensive player -- per Williams' agent, Ben Dogra.

ESPN and NFL Network first reported the development.

DT Albert Haynesworth previously held the record for a defender: seven years, $100 million ($41 million guaranteed) from the Redskins in 2009.

The Bills can only hope their investment pays off better than Washington's did.

"There are great people here. Caring and compassionate people that definitely have your back and I see that already," said Williams. "I just feel completely welcome and look at me as a person and somebody that can come here and help out so that his where I want to be the person to help out."

The No. 1 pick of the 2006 draft -- he was famously selected ahead of Reggie Bush -- Williams had 53 sacks in six years with Houston but missed the final 11 regular-season games of 2011 and the playoffs with a torn pectoral muscle. Factor in a hernia in 2010, and he's missed 14 games over the past two years.

Williams had made a successful transition from 4-3 defensive end to 3-4 outside linebacker with five sacks in five games last year. However the emergence of OLBs Connor Barwin and Brooks Reed in Williams' absence leaves Houston in good shape defensively.

Williams should supercharge a Buffalo pass rush that hasn't gotten much from oft-injured OLB Shawne Merriman or anyone else lately. The Bills garnered 29 sacks in 2011, though 10 came in one game vs. the Redskins.

"I know that's what we have here and to me that is one huge sell is those two guys (Kyle Williams and Marcell Dareus)pushing the pocket. Then hopefully I get the sacks, hopefully that's how it turns out," said Williams.

Now things could get tougher for Patriots QB Tom Brady, the Jets' Mark Sanchez, and whoever is taking snaps in Miami.

"I told him not to feel the pressure of having to be some kind of unbelievable player, unbelievable leader, and unbelievable entity of our football team," said Bills headcoach Chan Gailey. "He's a great player in his own right or he wouldn't be standing up here. He wouldn't be where he is. Just go do what you do and he'll make us better. This takes us one more step closer to where we want to be."

Other NFL quarterbacks are breathing a little easier. Lions QB Matthew Stafford re-tweeted this from Packers counterpart Aaron Rodgers:

"@AaronRodgers12: Congrats to Mario Williams signing in buffalo... far away from the NFC north, thanks big guy" Ditto

Williams has been in Buffalo since free agency began Tuesday, talking to the team and later touring the region with his fiancee.

He would almost surely return to defensive end for the Bills, who are reverting to a 4-3 alignment under newly promoted DC Dave Wannstedt. Williams would headline a front four that includes Pro Bowl DT Kyle Williams and DT Marcell Dareus, the No. 3 overall pick of the 2011 draft.