File Photo: Former British prime minister Tony Blair is shown ahead of a meeting at the EU Charlemagne building in Brussels, on November 6, 2019. AP
The Labour party's most successful leader, who won three successive general elections, was made Sir Tony in Queen Elizabeth II's New Year's Honours list.
The announcement was defended by the Conservative government, but several online petitions want it rescinded. One on change.org, accusing Blair of "war crimes", has drawn more than one million signatories.
Blair said he had accepted not just for himself but for the "dedicated, committed people" who had worked with him in government and "provided a lot of change to the country".
"And of course there would be people who object to it strongly. That's to be expected," he told Times Radio.
"There are some people who want to say the only thing the government did was Iraq and ignore all the rest of the things we do," Blair added.
But he stressed "you don't occupy a position of leadership and take decisions without arousing a lot of opposition, and so it didn't surprise me".
The Queen personally appointed Blair as "Knight Companion of the Most Noble Order of the Garter", the most senior order of knighthood.
She previously knighted former Conservative prime minister John Major in this way in 2005.
Blair, now 68, defeated Major with a landslide Labour victory in 1997 and spent a decade in office.
His successes included securing peace in Northern Ireland, investments in health and education, and expanding gay rights. But he was widely reviled at home for his support for the 2003 US-led invasion of Iraq.
Senior Conservative minister Michael Gove, while noting their political differences, said this week that Blair was an "outstanding statesman and performer".
Current Labour leader Keir Starmer said Blair had earned his knighthood, arguing he "made Britain a better country".