On top of Federer, Djokovic, Haas, Raonic, Monfils and Berdych winning their opening round match-ups, Sam Querrey, John Isner, Philipp Kohlschreiber, Julien Benneteau, Denis Istomin and Jarkko Nieminen also recorded victories.
Meanwhile, Polish No. 14 seed Jerzy Janowicz and 15th-seeded Spaniard Nicolas Almagro were among the biggest casualties in second day action.
Federer's opening round match was scheduled for the night session of Day 1 but was put off because of the New York weather, but despite having slipped to No. 7 in the world the 17-time Grand Slam winner had no trouble beating Slovakia's Grega Zemlja 6-3, 6-2, 7-5.
It was a clean performance from the 32-year-old Swiss great who hit 12 aces to two double-faults, 35 winners to 16 unforced errors and won a commanding 41-of-48 points on his first serve.
He will now face Argentine Carlos Berlocq in the second round after he beat Columbia's Santiago Giraldo 6-3, 3-6, 6-7 (6), 6-4, 6-2.
World No. 1 Djokovic also had little trouble winning his first round encounter beating Lithuania's Ricardas Berankis 6-1, 6-2, 6-2 and the Serb will now gear up to face German Benjamin Becker in the second round after he beat Czech Lukas Rosol 6-3, 3-6, 6-3, 6-4.
Big-hitting Canadian Raonic threw down 28 aces and hit an impressive 63 per cent of his first serves of which he won 86 per cent of them on his way to a commanding 6-3, 7-6 (6), 6-3 win over Italian Thomas Fabbiano.
Raonic will now face Spain's Pablo Andujar in the second round after he beat Dutchman Thiemo de Bakker 6-4, 6-4, 6-4.
Another big-hitter, American Querrey is also through to the second round after the 26th-seed won in four sets over Argentine Guido Pella, 7-6 (3), 4-6, 6-1, 6-2.
Querrey next faces Frenchman Adrian Mannarino who won through to the second round with a 4-6, 6-4, 6-2, 6-1 victory over Argentine Horacio Zeballos.
Giant American Isner also advanced into the second round in straight-sets beating Italian Filippo Volandri 6-0, 6-2, 6-3. The 13th-seed will now take on exciting and enigmatic Frenchman Monfils in perhaps the best second round match-up.
Monfils won through to the second round with a 6-1, 6-2, 6-0 win over Romanian Adrian Ungur.
Czech No. 5 seed Berdych also won through comfortably with a 6-1, 6-4, 6-1 victory over Italian Paolo Lorenzi. Berdych will next face Denis Kudla in the second round after he beat Jiri Vesely 6-2, 6-2, 6-7 (6), 7-5.
German Tobias Kamke beat American Steve Johnson 6-7 (4), 6-4, 7-6 (7), 6-2 to book in a second round match-up with Uzbekistan veteran Istomin who scored one of the day's big upsets with a 6-3, 6-1, 4-6, 6-3 victory over Spanish 15th-seed Almagro.
Another German, 12th-seed Haas, also had no trouble advancing into the second round with a 6-4, 6-4, 6-1 victory over Frenchman Paul-Henri Mathieu. Haas will next play Chinese Taipei's Yen-Hsun Lu in the second round after he beat Spain's Daniel Gimeno-Travers 6-4, 7-6 (5), 6-3.
Perhaps the biggest upset of the second day was Wimbledon semi-finalist and 14th-seed Janowicz being bundled out in the opening round to Argentina's world No. 247 Maximo Gonzales 6-4, 6-4, 6-2.
Gonzales, who advanced to the main draw at the US Open after winning through qualifying, will now face rising American Jack Sock in the second round after he downed Philipp Petzschner 7-6 (2), 3-6, 5-2 before the German qualifier retired with injury.
Another German, 22nd-seed Kohlschreiber, is into the second round after downing American Collin Altamirano 6-1, 6-3, 6-1. Kohlschreiber's next opponent is France's Edouard Roger-Vasselin after he beat Spaniard Albert Montanes 6-3, 6-2, 6-4.
American world No. 157 Donald Young is into the second round after a dominant 6-1, 6-0, 6-1 win over Slovak Martin Klizan. Young next faces Germany's Florian Mayer who beat Argentina's Juan Monaco when he withdrew midway through the third set with Mayer leading 6-4, 6-2, 3-0.
French 31st-seed Benneteau won in fourth tight sets against Poland's Michal Przysiezny 6-4, 5-7, 6-4, 6-4 and he will now play fellow Frenchman Jeremy Chardy after he beat Ukraine's Sergiy Stakhovsky 6-4, 4-6, 6-2, 4-6, 6-4.