The National Climatic Data Center, a division of the National Oceanic and Atmospheric Administration, noted the average temperatures over land and oceans were higher in 2014 than any year since 1880 when record-keeping began.
Last month also had the third-highest average global land temperature -- out of any December in the past 135 years -- at 2.45 degrees F above average, according to the agency.
The announcement marks the third time the past decade has produced record-setting warmth on an annual basis.
But 2014's warmth was historic, and it surpassed the prior records in 2005 and 2010, the agency said.
When 2014 is compared with the 20th-century average, the margin is much greater: Last year's average temperature over land and sea was 1.24 F above the last century's average, the agency said.
That figure marked a moment in the planet's recorded history.
"This was the highest among all 135 years in the 1880-2014 record, surpassing the previous records of 2005 and 2010," the agency said.
The federal report described how widespread was the blanket of warmth.
"Record warmth was spread around the world, including Far East Russia into western Alaska, the western United States, parts of interior South America, most of Europe stretching into northern Africa, parts of eastern and western coastal Australia, much of the northeastern Pacific around the Gulf of Alaska, the central to western equatorial Pacific, large swaths of northwestern and southeastern Atlantic, most of the Norwegian Sea, and parts of the central to southern Indian Ocean," the report said.
But the heat hardly means any loss of winter for some near-polar climates.
Snow cover in the Northern Hemisphere in 2014 was "near the middle of the historical record," the report said, citing data from NOAA analyzed by the Rutgers University Global Snow Lab.
"The first half of 2014 saw generally below-normal snow cover extent, with above-average coverage later in the year," the report said.