The win gave the Cottagers nine out of nine points in their final three games to escape almost-certain relegation. Instead, Reading and Birmingham City, both big winners on Sunday, joined last-place Derby in being dropped to the League Championship.
Kasey Keller was outstanding in goal for Fulham, which won at Fratton Park thanks to former Liverpool midfielder Danny Murphy's 76th-minute strike.
Keller, who won the starting job late in the season after arriving as a free agent in late August, did well to stop three long-range shots by Croatia international Niko Kranjcar.
Brian McBride and Clint Dempsey also started for Fulham against Pompey, the FA Cup finalist hat finished the EPL season with four straight losses.
For the second straight year, an American led Fulham in goals. Dempsey finished with a team-high six league goals in 2007-08. Last season, McBride led the Cottagers with nine goals. He finished four goals -- including a key goal in Fulham's 2-0 win over Birmingham on the second-to-last day of the season -- in 2007-08.
Carlos Bocanegra, relegated to a reserve role late in the season, was on the bench. Eddie Johnson, whose first season at Craven Cottage was a major disappointment, did not suit up.
- PORTSMOUTH-FULHAM SUMMARY:
May 11 in Portsmouth
Portsmouth 0 Fulham 1. Goal: Murphy 76.
Portsmouth -- Ashdown, Johnson, Distin, Pamarot, Hreidarsson, Utaka, Diarra (Muntari 83), Pedro Mendes (Davis 73), Kranjcar, Defoe, Kanu (Baros 73).
Fulham -- Keller, Stalteri, Hughes, Hangeland, Konchesky, Davies, Murphy, Bullard, Dempsey (Nevland 72), Kamara (Andreasen 85), McBride.
Referee: Mark Clattenburg.
With American Tim Howard in goal, Everton beat Newcastle, 3-1, to clinch fifth place and assure its return to the UEFA Cup.
PLAYER (TEAM) GP-G
Brad Friedel (Blackburn Rovers) 38-0
Marcus Hahnemann (Reading) 38-0
Clint Dempsey (Fulham) 36-6
Tim Howard (Everton) 36-0
Jonathan Spector (West Ham) 26-1
Eddie Lewis (Derby County) 24-0
Carlos Bocanegra (Fulham) 22-1
Bobby Convey (Reading) 20-0
Brian McBride (Fulham) 17-4
Kasey Keller (Fulham) 13-0
Benny Feilhaber (Derby County) 10-0