Their 1,300km-long (800 miles) journey from Haryana to their home state of Bihar was cut short when the bus broke down in Barabanki district.
Some of the workers were still in the bus while others were sleeping next to it when the accident happened in the early hours of Wednesday.
According to a local police, the bus was "overloaded beyond its capacity".
Yamuna Prasad, superintendent of police in Barabanki, said some of the passengers decided to sleep next to the bus while the driver looked for a mechanic to fix the vehicle.
"It's an unfortunate incident. The bus probably broke down because it had about 140 passengers when its capacity was just 65. We are assisting the families," he said.
At least 30 people, some of whom are critically injured, have been admitted to hospitals in Barabanki.
Meanwhile, Prime Minister Narendra Modi tweeted his condolences and announced Rs 2,00,000 rupees as compensation for the families of the victims, and 50,000 rupees for those who were injured.