Tomasz Procko, 22, and Karol Szymanski, 29, had been delivering sofas to the Knightsbridge property on Friday morning when the balcony collapsed.
Mr Procko, of Greenford, west London, died at the scene while Mr Szymanski, of Wembley, north-west London, died later in hospital.
Both men were originally from Poland. Their next of kin had been informed.
Eight other people were treated for injuries, the London Ambulance Service said.
A neighbour, who wanted to remain anonymous, told BBC News: "They were trying to pull a couch up to the first-floor apartment with ropes.
"[It] was apparently too heavy. The fence broke off and fell on the workmen below."
Sinclair Johnston, an engineer who has worked on another property in the square, said the decorative railings could not be depended upon to support weight.
The decorative wrought-iron railing appeared to have fallen about 3.6m (12ft) to the ground, although the stone base of the balcony appeared undamaged.
Two men who died after they fell from a balcony at Cadogan Square in west London have been named by police.