"I'm motivated by service for equality, social justice and internationalism.
"The conclusion I've reached is that Government has to be replaced. The truth is that the Labour Party is the only car that could attain that aim. There's not any other plausible choice."
Mr Bercow functioned as a Tory MP for 12 years before he was chosen Speaker in 2009.
His career had been dogged by allegations of bullying from parliamentary employees, accusations he refused.
Mr Bercow was likewise the topic of extreme ire out of Brexit-supporting MPs who considered that a collection of rulings he created throughout his time as Speaker favoured Remain.
In September 2019he declared his intention to stand out in the function, in addition to MP for Buckingham, and vacated the Speaker's seat in the end of October that year.
He maintained this past year that there was a"conspiracy" to prevent him getting a chair at the House of Lords.
Labour nominated him to get a peerage following the Tories failed to do so, breaking with all the longstanding tradition that transpired are raised after they retire.
Asked if there's the chance of being advocated to get a peerage from Sir Keir Starmer, Mr Bercow told the Observer:"There has been no such debate and I've asked for no anything. This is not about revenge. That isn't what inspires me."
Shadow justice minister Karl Turner stated he was unsurprised that his"buddy" had united states, but had been"thrilled he has".
John McDonnell, who had been shadow chancellor beneath Jeremy Corbyn, said Mr Bercow was"scrupulously fair" in his treatment of MPs, including the former Labour leader.
"He won his admiration, particularly because of his struggle to safeguard the rights of Parliament.
On the other hand, nevertheless, pensions minister Guy Opperman said that it was"from bad to worse to" Sir Kier, including:"Labour are welcome to Bercow."
A senior Government source said:"This will surprise no one shows Labour remains the celebration of Remain."