But the accolade has sparked a backlash from critics, with some saying he doesn't deserve an honour, and others going further and branding him a "war criminal" for his decision to take Britain to war in Iraq.
The petition, started by Angus Scott, says, "Tony Blair caused irreparable damage to both the constitution of the United Kingdom and to the very fabric of the nation's society.
"He was personally responsible for causing the death of countless innocent, civilian lives and servicemen in various conflicts. For this alone he should be held accountable for war crimes.
"Tony Blair is the least deserving person of any public honour, particularly anything awarded by Her Majesty the Queen.
"We petition the Prime Minister to petition Her Majesty to have this honour removed."
Tony, who was British Prime Minister between 1997 and 2007, has come under fire repeatedly for his involvement in the war in Iraq.
Knighthoods have been bestowed regularly on former prime ministers.
Following the announcing, Tony said, "It is an immense honour to be appointed Knight Companion of the Most Noble Order of the Garter, and I am deeply grateful to Her Majesty the Queen.
"It was a great privilege to serve as prime minister and I would like to thank all those who served alongside me, in politics, public service and all parts of our society, for their dedication and commitment to our country."
Blair has come under fire since receiving a Knighthood, with some branding him a war criminal for his decision to take Britain to war over Iraq.
Amid the backlash against his honour, Commons Speaker Sir Lindsay Hoyle said he thought all former prime ministers should be offered a knighthood.
Speaking to BBC Radio 4's Today program he said, "Whatever people might think, it is one of the toughest jobs in the world and I think it is respectful and it is the right thing to do, whether it is to Tony Blair or to David Cameron. They should all be offered that knighthood when they finish as prime minister."
