Coughlin was handed the job in 2004 following a nine-year stint at the Jacksonville Jaguars and went on to enjoy huge success over his 12-year tenure, including winning two Super Bowl championships.
However, the Giants missed out on the playoffs for the fourth consecutive campaign this year, in addition to posting a third straight losing season for the first time since a run of eight between 1973 and 1980.
Coughlin's time with the franchise was widely expected to come to an end in the close-season, and that belief intensified when he invited his entire family onto the pitch before the Giants' 35-30 home loss at the hands of the Philadelphia Eagles on Sunday.
"I met with John Mara and Steve Tisch this afternoon, and I informed them that it is in the best interest of the organisation that I step down as head coach. I strongly believe the time is right for me and my family, and as I said, the Giants organisation," Coughlin said in a statement.
"It has been an honour and a privilege to serve as head coach of the New York Football Giants. This is a not a sad occasion for me. I have spent 15 years with this organization as an assistant and head coach and was fortunate to be part of three Super Bowl-winning teams. A Lombardi Trophy every five years is an achievement in which we all take great pride.
"Obviously, the past three years have not been what any of us expect, and as head coach, I accept the responsibility for those seasons. I think it has been evident these last 12 years here how much pride I take in representing this franchise. I am gratified and proud that we were able to deliver two more Lombardi trophies to the display case in our lobby during that time. That is a tribute to our players and staff, and it was truly fulfilling to be the leader of those teams."
Coughlin ends his time as Giants coach with a record of 110-92, including playoff games, while his regular season total of 170 wins overall puts him 12th in the all-time list for NFL head coaches.