The Blues narrow victory masked the number of chances they created and could have paid the price for their profligacy had Pompey not missed a penalty.
But in the end it is Chelsea who earn the accolade of League and Cup double winners.
At the end of the end of a one sided first half the score was 5-1 to Chelsea.
Unfortunately for the Premier League Champions this was not goals scored but the number of times they had hit the woodwork compared to Pompey.
The tempo for the half was set after only 3 minutes when Frank Lampard fired wide after Nicolas Anelka's initial shot had been blocked.
Then the woodwork began to have its influence on proceedings as Portsmouth were pushed back on the defensive.
Lampard hit a swerving effort against the frame from 25 yards with David James well beaten.
Anelka then brought a fine save out of the keeper before Didier Drogba was twice foiled by Aaron Mokoena blocks.
Then totally against the run of play Portsmouth had a marvellous chance go in front as Kevin Prince-Boateng's mishit shot found Frederic Piquionne who from close range could only direct his effort against keeper Petr Cech and onto the frame of goal.
After 26 minutes Salomon Kalou made a case for the worst miss in an FA Cup final.
Ashley Cole broke into the penalty area and squared the ball for Kalou, who from six yards and with the goal gaping fired against the cross bar.
Drogba then thought he had given the Blues the lead when his free kick was pushed onto the bar by James and the ball bounced down onto the line.
The Ivory Coast hit man then hit the outside of the post as the keeper dived at his feet.
Chelsea substitute Juliano Belletti made a rash challenge on Aruna Dindane and referee Chris Foy had no hesitation in awarding the spot kick.
But Boateng made a poor attempt from twelve yards and Cech, despite diving the wrong way, saved with his legs.
Within two minutes the Champions took a deserved lead.
Drogba bent a perfect free kick around the Pompey wall, and whilst it hit the post this time it bounced into goal, much to the relief of the Blues supporters.
Kalou then dragged a shot wide and Drogba forced a block from James before Portsmouth made a series of substitutions and suddenly began to look threatening.
Dindane had a couple of half chances as Chelsea lost some of their swagger but then were handed the perfect opportunity to settle the game with three minutes remaining.
Lampard was clearly brought down in the penalty area but the England international picked himself up and incredibly pulled his spot kick wide of the post.