Didier Drogba maintained his remarkable knack of scoring at Wembley Stadium with the winner from a 59th minute free-kick after Chelsea had hit the woodwork five times in the first half while Frank Lampard missed a late penalty.
Chelsea overcame a resilient Portsmouth side, who made a mockery of their pre-match billing as lambs to the slaughter, to win a dramatic FA Cup final 1-0 and clinch their first League and Cup Double on Saturday.
Didier Drogba maintained his remarkable knack of scoring at Wembley Stadium with the winner from a 59th minute free-kick after Chelsea had hit the woodwork five times in the first half while Frank Lampard missed a late penalty.
In an astonishing match of twists and turns, Portsmouth's Kevin-Prince Boateng, who had scored from the spot in the semi-final at Wembley, saw his 56th minute penalty saved.
The triumph gave Chelsea a second straight FA Cup final victory, after they beat Everton last season, and was a third success in four seasons for the west London side.
It was Chelsea's sixth FA Cup triumph and fifth in 13 years as they became the seventh English club to win the double and the first team since Arsenal in 2003 to retain the trophy.
Chelsea manager Carlo Ancelotti, who has won the Double in his first season in England, told reporters afterwards: "Its a fantastic victory for me, I am very happy.
"We won't do anything special to celebrate, I will follow my players and my friends. Wine, sure, champagne. It is right to have a celebration, the team had a fantastic season."
"It has never happened in my career to hit the bar or post five times in one half... and we didn't start too well in the second half but I was not worried because we were in control of the game and had chances to score."
Portsmouth manager Avram Grant said, "It was a very difficult season. It is a season I will not forget. I have won a lot of games in my life, trophies and everything, but this was unbelievable. We always played against the odds."
In the first final between the champions and the bottom team in the top flight, Chelsea dominated the first half but were thwarted on five occasions when Drogba (twice), Frank Lampard, Salomon Kalou and John Terry all hit the bar or post.
Despite the pressure on their team, Portsmouth's incredibly vociferous fans made the greater noise inside the sun-drenched stadium and stayed to applaud their players even after defeat.
The match only turned Chelsea's way when Boateng's penalty, awarded after Chelsea's Brazilian substitute Juliano Belletti brought down Aruna Dindane, was saved by Petr Cech's legs.
Drogba fired home a 25-metre free-kick three minutes later that went in off the inside of a post to maintain his record of scoring in all of the six competitive matches he has played for Chelsea at Wembley -- three semi-finals and three FA Cup finals.
Lampard fired wide from the spot in the 88th after Michael Brown clattered into him but Chelsea had already just about done enough to become the seventh club in English history to win the Double, the 11th time the feat has been achieved.
Chelsea were quoted at 5-1 on to beat Portsmouth who are in administration, have debts of £138 million ($201.2 million) and finished bottom of the Premier League.
Some pundits had predicted a record FA Cup final victory following Chelsea's 8-0 trouncing of Wigan Athletic when they clinched the league title at Stamford Bridge last Sunday.
But Portsmouth, many of whose players may have been playing their last match for the south-coast club because of the financial problems and relegation, weathered the storm and at times dominated Chelsea for possession and passing.
However, the Londoners had only one first half scare with Cech producing a reflex save to deny Frederic Piquionne.
Pompey's first close shave came after 14 minutes when Lampard shot against the outside of David James's left-hand post with a 25-metre drive.
Kalou was guilty of one of the most blatant misses in any Cup final after 27 minutes when he shinned an Ashley Cole cross against the bar in front of an open goal from four metres.
Chelsea captain Terry and Drogba, twice, also hit the woodwork before halftime.
The Ivory Coast striker, who will lead his country at this year's World Cup finals, showed his utter frustration by smacking the post with his hand.
Chelsea had four other chances in the opening period but needed a stunning reflex save from Cech to keep out an instinctive close-range effort from Piquionne after 22 minutes.
Portsmouth had the brighter start in the second period but there was an air of inevitably about the outcome once Boateng saw his penalty saved and Drogba scored.
The icing on the cake for Chelsea's England defender Ashley Cole was a place in the record books as he climbed the steps to the Royal Box and collected his sixth FA Cup winners' medal.
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