Both matches were delayed by rain at the All England Club, but the interruptions didn't deter the top-seeded Djokovic, who reached the semis with a 6-4, 6-1, 6-4 decision over 31st-seeded German Florian Mayer.
The Serb fired seven aces while breaking Mayer's serve five times en route to the victory, outpacing the German 50-14 on winners while improving to 44-2 over his last seven Grand Slams.
Six-time Wimbledon champ and No. 3 seed Federer, meanwhile, had little trouble with 26th-seeded Russian Mikhail Youzhny, downing him 6-1, 6-2, 6-2 in 92 minutes.
The Swiss broke Youzhny six times in the rout, which was witnessed by Britain's Prince William and his wife Kate.
Djokovic and Federer will meet Friday for the 27th time -- but for the first time ever at Wimbledon. Federer holds a 14-12 career advantage in the match-ups, but the Serb has won six of their last seven meetings.
Also gaining the semis Wednesday were fourth-seeded Andy Murray and No. 5 seed Jo-Wilfried Tsonga of France.
Murray managed to get by No. 7 seed David Ferrer of Spain 6-7 (5-7), 7-6 (8-6), 6-4, 7-6 (7-4) in a Centre Court nightcap that was delayed by rain while the pair were tied at 5-5 in fourth set.
Murray -- a three-time Grand Slam runner-up -- is seeking to become the first British man to reach a Wimbledon final since 1938.
Tsonga, meanwhile, made his second straight semifinal with a 7-6 (7-5), 4-6, 7-6 (7-3), 6-2 victory over German Philipp Kohlschreiber, needing 2 hours, 48 minutes to post the win.