Mr Yadav said this election will end the BJP's "negative politics".
A Samajwadi Party fortress since 1998, the Kannauj Lok Sabha constituency was breached by the BJP in 2019, when Subrat Pathak won by a margin of about 12,000 votes, narrowly defeating Dimple Yadav, wife of Samajwadi Party chief Akhilesh Yadav.
Ending weeks of speculation, Mr Yadav has now decided to throw his hat in the ring from the constituency, replacing his nephew Tej Pratap Yadav, who had been declared the candidate earlier. While the decision was prompted by discontentment among Samajwadi Party workers, who wanted Akhilesh Yadav to contest from the seat, it has turned Kannauj into a prestige battle.
The BJP, which had secured 303 seats in the 2019 Lok Sabha elections, has set itself an ambitious target of winning 370 on its own this time around, and the opposition INDIA bloc is looking to secure a majority so it can form the government. For both sides, the most important battleground is Uttar Pradesh, which sends 80 MPs to the Lok Sabha, the highest, by far, of any state.
The BJP had won 62 constituencies in the state in 2019, when the Samajwadi Party was in an alliance with the Bahujan Samaj Party, and the challenge it faces this time is from the SP and the Congress, which are fighting 63 and 17 constituencies respectively.
Akhilesh Yadav has won from the Kannauj constituency - which was also held by his father Mulayam Singh Yadav before him - thrice and held it from 2000 to 2012, when he vacated it after becoming chief minister. His wife, Dimple Yadav, was then elected unopposed in a bypoll and won the seat again in 2014, before losing to Subrat Pathak in 2019.
Filing his nomination from the constituency on Thursday, Mr Yadav said this election will end the BJP's "negative politics".
"The people and party workers wanted me to contest from here as the SP candidate. I hope I will get the blessings of the people. When I came here for the first time after Netaji (his father and SP founder Mulayam Singh Yadav) asked me to contest from here, top leaders, including Janeshwar Mishra, Amar Singh, Azam Khan, Netaji were there. This election here will end the negative politics of the BJP. The fragrance of Kannauj, which is the city's identity, will spread again," the SP chief was quoted as saying by news agency PTI.
Asked about the delay in the announcement of his candidature, he said, "There is an old saying: Strike the iron when it is hot. I am here at the right time."
Subrat Pathak, who is the BJP candidate from the seat again, has compared his contest against Mr Yadav to an India-Pakistan match and said that it will be an interesting one.
Mr Yadav's sister-in-law Aparna Yadav, who joined the BJP a few years ago, has also said that winning the seat will no longer be easy for the Samajwadi Party.
Kannauj will vote in the fourth phase of the Lok Sabha elections, on May 13, and results will be declared on June 4.