The case is now in the penalty phase where it will be decided if he should get the death penalty or life in prison.
Yandamuri, who represented himself during the trial, showed no emotion as the guilty verdicts were read.
"I think it's fair to say that he was stunned. He thought he was gonna have a different verdict," said Henry Hilles, standy-by defense lawyer.
The 28-year-old information technology worker, who came to the U.S. on a work visa from India, was convicted of killing 10-month-old Saanvi Venna and her 61-year-old grandmother Satyavathi Venna.
"We've gotten one step closer in the closure of this for the Venna family. It's been a long struggle for them - two years," said Kevin Steele, first assistant district attorney.
Prosecutors argued that Yandamuri plotted to kidnap Baby Saanvi for ransom to feed his gambling habit, which was spiraling out of control.
However things didn't go as planned and police say he later confessed to the killings.
Yandamuri argued during his testimony that the confession was coerced and tried to blame two strangers who he said forced him to do it.
However, he never explained how he encountered the men or why he didn't go to police for three days.
Yandamuri's stand-by lawyers believe he made a mistake in choosing to represent himself.
"As a lawyer representing him, I would have gone in a different direction and hopefully would have come to at least save his life," said Stephen Heckman, stand-by lawyer.
Late Thursday, during the penalty phase of the trial, the defense presented Yandamuri's mother, who travelled from India.
She testified that her son was traumatized by the loss of his father, who was a police officer, at the hands of terrorists back home. She also begged the jury to spare her son's life.
"I think it helps to paint a picture of a troubled boy. He went through a whole lot and it helps to explain how he could have gotten into this mess," said Hilles.
"The defendant has his mother to beg for his life but the same opportunity was not given by the defendant for Saanvi Venna's mother to beg for her life," said Steele.
The penalty phase of the trial is set to resume Friday.