Despite having the support of just 6 percent of members, according to YouGov, Ms Nandy has thrown her name in the hat. She gave a warning to fellow party members in her announcement via the Wigan Post.
She said: “Unless we change course, we will become irrelevant.”
Labour suffered an unprecedented defeat in December’s General Election to the Conservative Party.
Ms Nandy laid out her vision for Labour via an article in The Guardian.
She said: “Now is not the time to steady the ship or try not to oversteer.
“What is needed are the hard yards of winning the argument inch by inch in town halls, workplaces and pubs.
“This is where we fight to regain people’s trust.
“The next Labour leader will have to be up for a scrap – willing to run to the places we are loathed, take the anger on the chin, make and win the argument.”
READ MORE: Robert Peston warns Boris Johnson help from Farage to backfire
Birmingham Yardley MP Jess Phillips also confirmed her candidacy.
In a campaign video she said: “I wasn’t sure if I was going to stand in this contest but listening to the debate in the days after the election, I thought, we’ve got to elect someone who gets it.
“Someone who understands how serious this defeat was.
“We’re a party named after the working class who has lost huge parts of its working-class base.
DON’T MISS: Real reason David Miliband was not elected to be Labour leader?
“Unless we address that, we are in big trouble.”
A spokesperson for her campaign said: “The Labour party membership, affiliates and supporters will be looking to this contest as a moment we can turn the page on what happened in December.
“They will want a proper say on what comes next for Labour. They deserve nothing less.”
A YouGov poll suggested that Kier Starmer was the frontrunner, with Rebecca Long Bailey in second, and Ms Phillips coming in third spot.
Political group Momentum, which began after Jeremy Corbyn became Labour leader in 2015, is yet to announce which member it will back.
However, a spokesperson said: “We have got this incredible people-powered campaign machine and we will be throwing it behind a leftwing leadership candidate.
Jeremy Corbyn said following his party’s heavy defeat that he would stay on as leader for the time-being, citing the reason as for a “period of reflection”.
