The court disqualified Marcos from holding public office, but she can remain a member of the House of Representatives while appealing the decision.
Neither Marcos nor her lawyers were present when the Sandiganbayan justices promulgated the decision to convict her for seven counts of graft.
She was given 30 days by the anti-graft court to explain her absence during the promulgation.
Marcos died in 1989 while still in exile.
Ferdinand Marcos, who along with his cronies was accused of pilfering $10 billion from the Philippines, fled with his family to the United States after a people's uprising ended his 20-year rule in 1986.More news: Vietnam to join Formula One Calendar from April 2020
The charges relate to alleged illicit financial dealings with Swiss-based NGOs while serving in her husband's government in the 1970s and 80s.
"So this is not yet final and executory", assistant special prosecutor Ryan Quilala told reporters. "The decision is a welcome relief and mitigates the pain of the past but only a full and voluntary acknowledgment by the Marcoses of their deeds can we say that closure is coming", he added. Imelda Marcos in particular was known for her flaunting her opulent lifestyle while the country languished in poverty and civil unrest.
The court's decision came almost three decades after the case was filed. The Sandiganbayan on Friday found her guilty in seven of these cases involving about $200 million.
"This points to how long and therefore frustrating the Philippine judicial system is", said opposition lawmaker Francis Pangilinan.
Imelda Marcos, the widow of the late Philippine dictator Ferdinand Marcos, was ordered arrested by the anti-graft court and sentenced to at least six years in prison.More news: India gets United States waiver for development of strategic Chabahar Port in Iran
Ferdinand Marcos had placed the Philippines under martial rule a year before his term was to expire. She ran for congress and won while her appeal was underway.
The younger generation of Marcoses have led high-profile careers, despite the dark past associated with their name.
Three generations of the Marcos clan are once again running for office in Ilocos Norte, the family's stronghold, in the 2019 elections.
Imelda's son, also named Ferdinand, nearly won the separate election for vice president that year.More news: Oil tanker rams into Norwegian frigate, leaving eight injured