In 1908, after having already attempted two trips to the North Pole, Peary and his party sailed to Ellesmere Island (at the far north of Canada) on the USS Roosevelt. In early March, 1909, the expedition (Matthew A. Henson, Dr. John W. Goodsell, Donald B. MacMillion, Ross G. Marvin, George Borup and Captain Robert Bartlett) left their base camp at Cape Columbia and headed north in dog sleds (which Henson built). Peary, Henson and four Eskimos reached the North Pole on April 6, 1909 (the others turned back at various places along the way). It is now thought that Peary and Henson may have been 30-60 miles (50-100 km) short of reaching the pole (because of navigational mistakes that were made). Frederick A. Cook (who had accompanied Peary on an earlier expedition) later claimed to have reached the North Pole before Peary, in April 1908; this claim was later rejected completely as a cruel hoax.

Peary led many earlier expeditions, including explorations of Nicaragua (looking for a good location for a canal linking the Atlantic and Pacific Oceans). These exploratory trips included:

• 1888 (Nicaragua)
• 1891-92 (Nicaragua)
• 1893-95 (with Hugh J. Lee and Henson: charted the ice cap of Greenland - the expedition members almost starved to death)
• 1896 (meteorite collection in the Arctic)
• 1897 (meteorite collection in the Arctic)
• 1898-1902 (many Arctic expeditions)
• 1905-06 (North Pole - they only made it to 87°06' N)
• 1908-09 (North Pole - successful)