Cardinal Roberto Tucci and Father Pasquale Borgomeo were given suspended 10-day jail sentences.
The Italian court also ordered them to pay damages and court costs.
Two scientific studies have suggested a field of Vatican Radio broadcasting antennas north of Rome may have caused high rates of cancer in the area.
The first, in 2001, found that magnetic fields around the transmitters were much higher than normal limits allow.
The giant masts beam news programmes worldwide in 40 languages.
A first trial was stopped in 2002 when a judge ruled that Italy had no jurisdiction over the radio station because it was part of the Vatican City, an independent sovereign state.
But that decision was later overturned and Cardinal Tucci, the station's president, and Rev Borgomeo, its director general, went back on trial.
"After so many delays and so much wasted time, today we have achieved an important success which underscores the need to protect people from the risk of 'electro-smog'," said Roberto Della Seta, chairman of environmental group Legambiente, after the verdict.
Raffaele Capone, who heads a residents association in the Cesano area, said: "We hope that it will be removed from our territory so that we can finally live in peace."
Some residents complained the transmissions were so strong they could hear radio broadcasts through their domestic lamps.
However, Vatican Radio programme director Rev Federico Lombardi said: "We're stunned".
He vowed to appeal, saying emissions were within international limits and "in line with accords between Italy and the Vatican".
The judge said the level of damages
payable by the defendants would be
set by a civil arbitration body. It could run into many millions of