Federal Judge Joan Lenard gave a sentence of 262 months (21 years, 10 months) and five years probation to Antonio Guerrero, for gathering and relaying US military information to Cuba. The sentence was just over the 20 years prosecutors had sought.
Guerrero committed "very serious offenses against the US," the judge said.
"The government did not present evidence that the defendant obtained top secret information, but he worked to obtain such information," Lenard stressed.
Attorney Leonard Weinglass, who represented Guerrero, said the outcome was not what he expected.
"I'm surprised with this decision," said Weinglass. "We negotiated an agreement with the government in good faith. Hopefully, he will be at home in seven years."
Cast as heroes in Havana, the "Cuban Five" -- Guerrero, Gerardo Hernandez, Rene Gonzalez, Ramon Labanino and Fernando Gonzalez -- were arrested in 1998 and convicted three years later. Guerrero, 50, is an airport construction engineer by training born in the United States to Cuban parents.
Earlier, three of them were sentenced to life in prison and the other two were given sentences of between 15 and 19 years. Cuba regards them as political prisoners and has lobbied intensely for their release.
Lenard this week accepted requests from Labanino and Gonzalez' attorneys to delay their sentencing pending a probe into whether the US government had determined how much damage the spies' work had caused.
An appeals court earlier found the original sentences for the Cubans to be excessive and ruled that new ones should be handed down.
Court documents claim the Cubans were looking for US military information, and to monitor groups of Cuban exiles opposed to the Havana government.
Cuba has acknowledged the men were agents but claims they were working to stop terrorist attacks on Cuban soil.
"While (the new sentence) is not as absurdly exagerrated as the prior one, it is also unfair," official Cuban websites Antiterroristas and Cubadebate said on learning of Guerrero's new sentence. They said the reduced sentence was a "result of international solidarity and the strenuous effort of his defense attorney."
The court developments come amid a slight easing in tensions between the two countries, dating back to the Cold War. The neighbors do not have full diplomatic ties, and the United States has had an economic embargo on Havana for decades.
In April, US President Barack Obama authorized travel and money transfers to the island by US nationals of Cuban descent and a month later proposed restarting US-Cuba talks on migration issues suspended since 2003.
But while Cuban President Raul Castro has said he would be willing to swap jailed political dissidents for the five imprisoned men, the US government has rejected the idea.
The United States also has said it will not, for now, seek to end the full trade embargo, which dates to 1962. Instead it has urged Havana to show progress on human rights, an approach that has not previously borne fruit.
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