Congress candidate Manish Tewari defeated the BJP's Sanjay Tandon to secure victory from Chandigarh's lone Lok Sabha seat.
Tewari, a former Union minister, won by a slender margin of 2,504, according to data on the Election Commission website.
The senior Congress leader said his win was a victory for justice, peace and stability.
"Grateful to Chandigarh and my beloved people for their blessings in making me win the elections. This is the victory of justice, peace and stability over divisive politics -- a true win for democracy," Tewari said. "The people of Chandigarh are the torchbearers of safeguarding our Constitution. I guarantee that together we shall usher in a bright progressive future for Chandigarh, as promised. Thank you once again for your faith in my leadership," he said.
Tewari maintained his lead over Tandon since counting began, despite Congress workers alleging later on Tuesday that there was a delay in declaring the final result.