Amarinder Singh had earlier been rushed to Sonipat's FIMS Hospital but he died during treatment.
A 40-year-old farmer from Punjab's Fatehgarh Sahib - one of tens of thousands who have been protesting against the centre's agriculture laws for nearly two months now - died by suicide at Singhu on the Delhi-Haryana border on Saturday after consuming a poisonous substance.
The farmer - identified as Amarinder Singh - told friends he was forced to take this step because the government had refused to listen to their demands - that the agriculture laws be repealed and the legal guarantees be offered for MSP (minimum support price).
He said that he hoped his death would bring success to the farmers' movement.
Mr Singh had earlier been rushed to Sonipat's FIMS Hospital but he died during treatment.
His body was then sent to the mortuary at the Government Hospital, where a post-mortem has been scheduled for Sunday morning. The body will then likely be handed over to other farmers at the protest site because police have, so far, been unable to trace Amarinder Singh's family.
This is the second farmer death to have been reported this month; last week a 75-year-old farmer was found dead at a protest site near the Delhi-Ghaziabad border.
The body of Kashmir Singh Ladi, from Uttar Pradesh, was found with a note that said: "Till when shall we sit here in the cold? This government isn't listening at all. Hence, I give up my life so that some solution emerges."
Farmers say dozens have died - several by suicide - since the agitation began in November.
The farmers braved tear gas and lathi charges to reach the borders of the national capital, where they remain despite a freezing winter, and say they will not budge till their concerns are addressed.
The centre says these laws will help farmers eliminate middlemen and sell at markets and prices of their choice. The farmers fear it will rob them of MSPs (minimum support price) and, by dismantling government-controlled mandis, or wholesale markers, leave them at the mercy of the corporates.
Multiple rounds of talks have failed to yield a breakthrough, with the farmers insisting on legal guarantees for MSP and the scrapping of the laws. The centre has said the laws will remain, but has offered to form a committee to study other grievances - an offer the farmers have rejected.
The farmers have made little secret of their growing impatience at the stalemate; during the eighth round of talks, which were held Friday, placards appeared at the meeting with union ministers, reading: "We will (succeed in repealing the laws) or die".
A ninth round has been scheduled for January 15 - less than two weeks before the farmers take out a tractor rally - on Republic Day - to enter Delhi.