US District Judge Barbara Jones said in ordering the sentence: "A sentence of anything less would not reflect the seriousness of the crime"
The term is effectively a life sentence for the 63-year-old Ebbers, who built one of the biggest US telecom empires and became a symbol of the corporate scandals that rocked the financial world.
After prosecutors asked for the maximum sentence of up to 85 years, the judge said her reading of sentencing guidelines suggested a range of 30 years to life.
But she then said "30 years would be excessive," and decided on a 25-year term after hearing pleas from the defence about Ebbers' poor health and charitable work.
The sentence is nonetheless one of the stiffest in recent memory in a white-collar crime case and reflects the effort to crack down on corporate misconduct in the wake of the scandals at Enron, WorldCom and other companies that roiled financial markets and prompted legislative reforms.
Defence attorney Reid Weingarten argued for leniency, saying prosecution estimates of losses of some two billion dollars was an exaggeration and that much of this came from economic market forces and not fraud.
"A sentence of anything less would not reflect the seriousness of the crime"
US District Judge
In an emotional plea, Weingarten said Ebbers "has grieved from day one of the failure of WorldCom for those who lost money. He has grieved every day."
He also described Ebbers' charitable work, calling him "an angel" who had given more than $ 100 million to orphanages, schools and other organisations.