Ershad Sikder, who was unaware that preparations for his execution had been underway for several weeks, broke down in tears on Monday on learning that his final appeal had been rejected, the Daily Star said.
Sikder was convicted of 11 murders after his former bodyguard told police he had ordered the killing of at least 59 people and personally carried out 24. Some 20 cases against him were still pending.
Until his arrest, the six-times married Sikder enjoyed a lavish but violent lifestyle, killing anyone who got in his way, living in a palatial mansion and bathing in milk, according to media reports.
The execution of the crime lord brings to an end his 20-year reign of terror in the southwestern city of Khulna, 136km from the capital, Dhaka.
Khulna is notorious for its violence with politicians, businesspeople and occasionally journalists frequently attacked. Sikder had previously been a member of the country's two main political parties.
"He murdered people he did not like in any brutal way he wished," News Today said in a recent report on Sikder. "Cold-blooded killings were his favourite sport. Killing was his addiction".
Sikder was hanged at one minute past midnight on Tuesday morning.