Goals from David Silva, Jordi Alba, Fernando Torres and Juan Mata gave the world champions an easy victory over an Italian team down to 10 men through injury for the last half-hour.
The diminutive Silva scored with a rare header after a Cesc Fabregas pull-back in the 14th minute before a superb sprint finish from left-back Alba following a pinpoint Xavi pass doubled their lead four minutes before halftime.
Torres, who scored the winner in the final when they won the title in 2008, struck their third goal in the 84th minute before setting up fellow substitute Mata to add the final flourish in the 88th. Torres is the first player to score in two Euro finals.
The result is also the highest margin of victory recorded in either a European Championship or World Cup final.
"My team mates made history before and now I am doing so together with them in my first European Championship," said Spain's fullback Alba. "I am struggling to believe it but it seems to be sinking in little by little.
"I told my friends and family I was gong to score tonight and that's the way it turned out."
Stylish Spain
Italy had more possession than Spain in the opening half but when they did have a sniff of goal goalkeeper Iker Casillas maintained his astonishing record of not conceding a goal in the knockout stage of a tournament for the 10th successive match.
Spain have become the first European side to win three major tournaments following their success in Euro 2008 and the World Cup two years ago.
The only other team to win three successive major titles was Argentina who lifted the Copa America in 1945, 1946 and 1947 when that tournament was held annually.
Spain, who started without a recognised striker, were all artistry and guile in midfield while Italy, whose own creator Andrea Pirlo failed to shine, were handicapped by having only 10 men from the hour mark after using up all three substitutes.
The third of them, Thiago Motta, only lasted four minutes after replacing Riccardo Montolivo in the 57th before limping off with a hamstring injury.
Italy went close twice through second half substitute Antonio Di Natale but Mario Balotelli, the two-goal hero of their 2-1 semi-final win over Germany, rarely looked like scoring.
The opening goal came when Andres Iniesta split the Italy defence with an incisive pass to Fabregas who outpaced Giorgio Chiellini to get to the byline where he pulled the ball back to Silva who flashed his header past the helpless Buffon.
The second came when Alba tore past the static Leonardo Bonucci and planted a perfect left foot shot past Gianluigi Buffon. Torres then ran through to score the third after another Xavi through ball before setting up Mata with a deft flick.
