"Resigned from Vadodara LS seat. Due to people's affection got elected by historic margin. Will always remain grateful to people of Vadodara," Modi tweeted on Thursday evening.
The Lok Sabha Speaker will forward the resignation to the Election Commission, which will then declare Vadodara vacant after which fresh elections will be held for the seat.
In another tweet, Modi said, "I assure people of Vadodara I will leave no stone unturned in ensuring that Vadodara's development scales newer heights in the years to come."
Modi had won both seats by huge margins but it was expected that he would retain Varanasi, which was seen to have had an impact on the entire Poorvanchal region.
In a third tweet, Modi said, "I will represent Varanasi in Lok Sabha & I look forward to this wonderful opportunity to serve Ganga Maa & work for Varanasi's development."
Meanwhile, Samajwadi Party chief Mulayam Singh Yadav has vacated Mainpuri Lok Sabha seat and has retained Azamgarh.