Ghoochannejhad struck a brilliant first goal in England and goalkeeper Ben Hamer saved a last-minute penalty to boost Charlton's survival bid and send Leeds to a third straight defeat.
Striker Ghoochannejhad - he has his first name Reza on the back of his shirt - curled home the only goal of the game from the corner of the penalty area early in the second half to lift Charlton three points clear of the relegation zone.
The Iran international's first goal since arriving at Charlton from Standard Liege in mid-January secured the Londoners only their fourth league win on the road this season and did little to lift the gathering gloom at Elland Road.
But Charlton's success owed as much to Hamer, who saved superbly to deny McCormack's late spot kick after Charlton midfielder Diego Poyet had shoved Aidy White in the area.
Leeds, who are still waiting to learn the outcome of Massimo Cellino's protracted £25million takeover bid, have now lost four of their last five home games.
The Yorkshire club's future has effectively been placed on hold while a judge in London decides whether or not to uphold the Football League's decision to disqualify Cellino from taking control.
Leeds' form has clearly been affected as the latest saga at Elland Road rumbles on, with coaching staff and players receiving only half of their March wages last week.
Two straight defeats, the latest in sorry fashion against Doncaster on Saturday, and only one win in their previous nine matches has heaped more pressure on manager Brian McDermott.
In contrast, Charlton's Belgian boss Jose Riga appears to be winning over Addicks fans after replacing the popular Chris Powell on March 11.
Riga's inherited side are far too good on this showing to be relegated and in midfielder Diego Poyet, son of former Leeds assistant boss Gus who was in the stands, they possess one of the best teenagers outside the Premier League.
Defenders Stephen Warnock and Scott Wootton, plus midfielders Michael Tonge and White were recalled to Leeds' starting line-up as McDermott chased a second win in 10 matches.
Astrit Ajdarevic was back for Charlton following illness and fellow striker Joe Pigott and defender Dorian Dervite were also recalled by Riga.
Tonge spurned a golden chance to give Leeds the flying start they craved when he blazed off target after taking a super touch to bring down McCormack's free-kick into the penalty area.
But Charlton began just as brightly and Frenchman Dervite's low 25-yard shot forced Leeds goalkeeper Jack Butland into a full-length save.
Leeds striker Matt Smith's mis-hit volley from the edge of the area failed to trouble Charlton goalkeeper Hamer, while at the other end long-range shots from Ghoochanneijhad and Ajdarevic were comfortably held by Butland before the break.
Leading goalscorer McCormack stirred the crowd with a swerving 30-yard shot soon after the restart which bounced down close to the goalline after Hamer had touched the ball on to the crossbar.
Ajdarevic's low shot soon after lacked enough power to trouble Butland, but there was little wrong with Ghoochannejhad's brilliant 54th-minute effort that put Charlton ahead.
There was nothing on when he won the ball from Leeds defender Jason Pearce on the right-hand corner of the area, but the Iran international produced a sublime curling effort that nestled in the top corner.
McCormack fired over following half-time substitute Noel Hunt's fine cross as Leeds hustled to get back on terms, but that was as close as they got before Pearce's late header was blocked.
Poyet's push on White in the 90th minute appeared to have thrown Leeds a lifeline, but Hamer flung himself to his right to keep out McCormack's late penalty.