He was 79.
Singh, who was elected from the Kairana seat, is survived by five daughters.
Condoling his death Prime Minister Narendra Modi said on Twitter, "Anguished by the demise of MP and veteran leader from Uttar Pradesh, Shri Hukum Singh Ji. He served the people of UP with great diligence and worked for the welfare of farmers. My thoughts are with his family and supporters in this hour of grief."
BJP president Amit Shah said Singh's demise was an irreparable loss for the party.
More From This Section
In a tweet Union Minister of State for Parliamentary Affairs Vijay Goel expressed shock over Singh's death and said it was a huge loss for the BJP.
Before the UP Assembly elections last year, he had highlighted the issue of alleged migration of the Hindus from parts of his Lok Sabha constituency and its neighbourhoods.
The Lok Sabha is likely to be adjourned on Monday as a mark of respect to the BJP leader after paying tributes to him.