Hitting coach Rick Schu was also dismissed and pitching coach Bryan Price tendered his resignation.
Hinch does not have any prior managerial experience at any level. The 34-year-old former catcher wrapped up a seven-year Major League career following a 2005 season in which he played at Triple-A Scranton/Wilkes-Barre.
The following year, Hinch joined the Arizona front office, overseeing the organization's farm system. Under his direction, players like shortstop Stephen Drew, Micah Owings, Tony Pena, Mark Reynolds, Justin Upton and Chris Young reached the Majors.
Hinch had become a close confidant of Byrnes and the pair often watched games together this year in the general manager's suite at Chase Field.
While the move is likely to surprise some given Hinch's lack of managerial experience, it goes along with Byrnes' tendency to think outside the box when looking for solutions.
Hinch was regarded as a good leader on the field. A bright individual, he was an All-American player at Stanford and participated in the 1996 Olympics.
In 953 big league at-bats, Hinch hit .219 with 32 homers and 112 RBIs for Oakland, Kansas City, Detroit and Philadelphia.
BOB MELVIN'S RECORD
Hinch's first task will be trying to get the D-backs offense on track. The team ranks 15th in the National League in runs scored and several of its younger players, like Young and Conor Jackson, have struggled at the plate, along with veterans like Eric Byrnes.
Speculation about Melvin's job status has been circling for several days now with the D-backs, a team picked by many to contend for the National League West crown, off to a disappointing 12-17 start.
After the team raced out to a 20-8 start to the 2008 season, they slumped the rest of the way and were eventually passed by the Dodgers in September. As the season progressed it became clear that Melvin and Byrnes were drifting apart.
That gap widened this year after the team's tough start. Byrnes was noticeably absent from the team's recent eight-game road trip and comments made by team president, and CEO Derrick Hall on KTAR 620 AM, the team's flagship station, Thursday morning foreshadowed the move.
When the team buses arrived at Chase Field on Thursday night, word had filtered through the team that Melvin was going to be dismissed and multiple media outlets were already reporting it would happen.
While Melvin met with Byrnes in his office, players milled around the clubhouse awaiting word. But after a while, when it became evident none would be forthcoming, they dispersed.
After delivering the news to Melvin, Byrnes met with the coaches individually.
Price, a close confidant of Melvin and one of the game's most respected pitching coaches, chose to resign.
"I believe that Bob is an outstanding Major League manager," Price told MLB.com after leaving the clubhouse. "And it tears my heart out that he's not managing this ballclub any more. Our relationship extends beyond a working relationship. I hope more people, when they look at this, will understand and admire the work he did with this group."
Melvin was hired by the team on Nov. 3, 2004 and improved the team's win total by 26 games in 2005. After leading the D-backs to a National League-best 90 wins in 2007, Melvin was named the NL Manager of the Year and received a contract extension that runs through 2010.
"I think we all take responsibility for the way we're playing," ace Dan Haren said following Thursday's game. "It's unfortunate that [Melvin] is getting some of the heat. We're not playing up to our potential. Is it his fault? No. He can't go up there and throw the ball and hit the ball. I think if you ask every player in here they'll tell you they need to look inside and get more out of themselves and not point fingers."
While players expressed support for him in recent days, ultimately, their poor play on the field cost him his job.
"He's taken bullets for everybody," Price said. "He protects his players and throws everything onto his own shoulders and that's the type of guy he is. That deserves respect because he has shielded the non-performers from the criticism that perhaps their performance would inspire.
"I just want people to know that my feelings are that Bob has done an unbelievable job. My allegiance is to him as a friend, but it's really because I believe in the job he did and I was there every day of it. I know that somebody has to be held accountable for the performance and Bob was the guy. I admire the fact that he handled himself with the dignity and professionalism that he has, because he's taking bullets for a lot of people."