The outspoken Europhile and former deputy Prime Minister will be awarded the prestigious gong for political and public service.
But Nigel Farage, who led the victorious Brexit campaign last year, was again snubbed by the honours committee.
Mr Clegg has repeatedly called for the result of the EU referendum to be reversed, and even wrote a book titled How to Stop Brexit.
In the book, he claims: “There is nothing remotely inevitable about Brexit – except that it will be deeply damaging if it happens.”
The ex-MEP served as David Cameron’s deputy in the Conservative-Liberal Democrat in the coalition between 2010 an 2015.
Ukip education spokesman David Kurten tweetd: “UK establishment to knight Nick Clegg and Vince Cable, but ignores Nigel Farage.
“Says it all about the people currently in charge. Time to drain the swamp.”
And Daily Express columnist Leo McKinstry branded Mr Clegg’s award “a calculated snub towards Brexit supporters”.
He said: “Clegg’s knighthood is all the more offensive because the same liberal establishment decided to award nothing to Nigel Farage.
“Once again the real architect of our national freedom has been given no recognition at all.
“The contrast in the treatment of these two figures epitomises the warped, anti-British values of the politically correct ruling class.”
Mr Clegg was booted out of Parliament at June’s general election, being unseated in his Sheffield Hallam constituency by Labour’s Jared O’Mara.
Mr Farage earlier this week confirmed he was overlooked by the honours committee.
The former Ukip leader said: “Of course I have not got an honour of any kind – I am not a Remainer.
“Everyone of them got CBEs, they got knighthoods, quite extraordinary.”
However, four pro-Brexit Tory MPs were given knighthoods or damehoods – Graham Brady, Geoffrey Clifton-Brown, Christopher Chope and Cheryl Gillan.
Labour MP Mark Hendrick, who voted Remain, will also be knighted.
Commons Deputy Speaker Lindsay Hoyle will become a Sir, but it is not known how he voted in last year’s referendum.
The other political figure to be knighted is Prof John Curtice, who led the exit polls that accurately forecast the last four general elections.