Dhaka Metropolitan Sessions Judge KM Imrul Kayes handed down the verdict.
The lifers are Jabal-e-Noor drivers Masum Billah and Zobair Mamun and bus helper Asad Gazi. Asad was tried in absentia.
The court also fined them Tk 50,000, and they will have to suffer six months more rigorous imprisonment if they fail to pay the fine.
The court also acquitted two people — a Jabal-e-Noor bus owner, Jahangir Alam, and bus helper Enayet Hossain -- as allegations brought against them could not be proved.
The case proceedings against the owner of the second bus remained halted following a High Court order.
On October 25, 2018, owners of two Jabal-e-Noor buses Shahadat Hossain and Jahangir Alam, drivers Masum Billah and Zobair Sumon and assistants Enayet Hossain and Asad were indicted in the case.
According to the case statement, the accident took place amid a wild competition of drivers of the two buses of Jabal-e-Noor Paribahan on the road.
Diya Khanam Mim and Abdul Karim Rajib, first-year students of Shaheed Ramiz Uddin Cantonment College, were killed as one of the buses ploughed through some students in front of Kurmitola General Hospital on Airport Road in the capital.
The accident triggered a widespread protest by students, demanding safe roads and seeking justice for their fellows.
In its observation, the court said the killing of people due to apathy of drivers and helpers has turned into a craze in the transport sector which should be stopped.
Drivers and helpers engage in an unhealthy competition to appease their owners as they demand higher amount of money for daily deposit which contributes to accidents and deaths on roads, it said.
The transport owners should shun the tendency of earning excessive money while traffic police should also remain alert on the roads and check the driving licences of drivers, the judge said.
The court also hailed renowned actor and founder of Nirapad Sarak Chai Ilias Kanchan for his persistent movement for safe roads.