Moments later, Melgar, who had been free on bail since her arrest, was taken to a nearby jail, news.com.au reported.
She faces five years to life in prison and will return to court for sentencing on Thursday.
During the trial, prosecutor Colleen Barnett argued that the crime scene was not consistent with Melgar's story of a home invasion.
The court heard that her motive was to draw on a $500,000 life insurance policy.
"I would like to thank the jurors for their patience and attention throughout this long, difficult case," Ms Barnett said in a statement released by the district attorney's office.
"Jaime Melgar was by all accounts a wonderful man."
Defence lawyer Mac Secrest argued that there were problems with one of the former homicide investigators involved in the case and "a couple of cowboys" at the Harris County Sheriff's Office.
The lead investigator, who was later fired for backdating a search warrant in a different murder case, also took the stand for the defence.
The jury deliberated for about eight hours before the verdict was handed down.
The defence team and Melgar's family members declined to comment as they left the courtroom.
Melgar has maintained her innocence.
