Justice Felix Cacchione came down with his verdict Friday in Nova Scotia Supreme Court.
Aurora Breakthrough was seven weeks old when she died at the IWK Health Centre in July 2009.
The baby had a number of injuries — broken ribs, broken arm and leg bones, and blunt force trauma to the head — when she was taken to hospital.
The child's mother, Jane Gomes, received a conditional discharge with six months probation after pleading guilty to a charge of failing to provide the necessities of life.
Gomes testified against Rahman in December.
"The child was an impediment to pursuing his business interests," said Denise Smith, the Crown prosecutor. "He was frustrated by the demands of a young infant and the crying of a young infant in particular."
Cacchione rejected just about everything Rahman said, calling his testimony "evasive and argumentative" and labelled him a "manipulator."
Rahman wore a T-shirt advertising a company that shares his name.
He will stay in jail until sentencing. The sentencing hearing is set for Aug. 7.
"I still stand behind my client to what he had to say about his involvement in his daughter's death, and it's unfortunate that the judge did not accept what he had to say," said Don Murray, Rahman's lawyer.
The maximum sentence for manslaughter is life in prison.