The Swiss, bidding for a record sixth title at the Tour finale, needed the best part of an hour to take the opening set off one of the most tenacious competitors in tennis, but was untroubled after breaking through early in the second.
Federer will face the winner of the other semifinal between French powerhouse Jo-Wilfried Tsonga or Czech Tomas Berdych in Sunday's final. Should he win the title he would pocket the $1.63 million jackpot for an undefeated champion.
Ferrer went into the match with a 0-11 record against the 16-times grand slam champion and though he kept pace with the Swiss in the first set there was a feeling that he was merely staving off the inevitable.
The Spaniard had a glimmer of a chance at 4-5 in the opening set when Federer eventually held serve after five deuces, although he never had to save a set point.
Federer then played a brilliant point to reach 15-40 on the Ferrer serve in the next game and he converted his second point when his opponent went wide with a forehand.
He served out the set with ease and then pounced right at the start of the second set to take complete control.
That single break proved enough as he completed a routine victory in one hour 25 minutes. Victory also meant that Federer will end the year as world number three, moving back above Britain's Andy Murray who withdrew from the tournament with a groin strain.
On Friday, after staring elimination in the face Berdych ended up winning Group A with a 3-6, 7-5, 6-1 win over Fereer and thus avoided a semifinal against holder and red hot favourite Federer.
