Michelle Michael, 35, had taken the stand in her own defense and denied killing James Michael.
Authorities determined that the 33-year-old businessman was injected with a fatal dose of rocuronium, a paralyzing drug, as he lay in bed in couple's Morgantown home in November 2005.
Prosecutors argued that his wife drugged him, left for work, then returned later that morning to set fire to the bed in an effort to cover her tracks.
The defense suggested that James Michael, who co-owned a respiratory care provider, killed himself. But prosecutor Marcia Ashdown said suicide was impossible -- the autopsy showed he was dead before the fire began.
At the time, Michelle Michael was having an affair with an employee of her husband's and was dissatisfied with her work and marriage, prosecutors to told the jury. She also stood to gain $500,000 from her husband's life insurance and at least $200,000 from her home fire insurance.
As a nurse practitioner, she had worked in a hospital pediatric intensive care unit, would have had access to the drug and would have known its effect, prosecutors said.
The jury deliberated for about 11 hours over three days before finding her guilty of first-degree murder and arson.
No sentencing date has been set, but the jury recommended mercy: the mandatory life sentence with parole eligibility after 15 years.
Defense lawyer Tom Dyer said he is reviewing possible grounds for an appeal.