The attackers fired five rounds at Deven Shah in front of his son Atit on the plush Prabhat Road around midnight. Two of the bullets hit Shah, a senior police official said.
The family had just returned home after celebrating the birthday of Deven Shah's wife in a hotel in the Baner area, the official added.
Police have retrieved a CCTV footage of the area in which the two assailants are clearly seen.
"They told him to ask Deven Shah to come down," said Additional Commissioner of Police (South/North region) Ravindra Sengaonkar.
When the businessman and Atit came down, the men started talking to Deven Shah, who urged the duo to come to a sit out area of the building.
"While he (Deven) was going towards the area, one of the attackers fired at him from a close range," said Sengaonkar.
He said when Deven Shah, who was hit in the chest, ran towards the lift, the other attacker too fired at him.
According to another police officer, the attackers fled through the main gate of the building.
Deven Shah's son Atit gave them brief chase but they pointed the gun at him, the officer, attached to the crime branch, said.
"Deven Shah was rushed to a nearby hospital, where he died in the early hours today," the officer said.
Deven Shah, who owned Ambika Land Ventures, had entered some real estate joint ventures.
Atit told police his father did not have enmity with anyone, the ACP said, adding the motive behind the killing was yet to be ascertained.
"A probe is on and we are on right track," he said.
Police suspect the attack could be the fallout of a land dealing.
A case under relevant sections of the IPC was registered at the Deccan Gymkhana police station.