Initially recorded in the North Atlantic on February 4 2013, the wave has now been analysed by an expert committee of the World Meteorological Organisation (WMO) and marked as a new world record.
It followed the passage of a very strong cold front, which produced winds of more than 50mph in the area between the UK and Iceland.
The buoy that recorded the wave is a part of the Met Office’s network of marine automatic weather stations.
The WMO commission for climatology’s extremes evaluation committee - made up of scientists from the UK, US, Canada and Spain - classified it as “the highest significant wave height as measured by a buoy”.
The previous record of 18.275m was measured on December 8 2007, also in the North Atlantic.
WMO assistant secretary-general Wenjian Zhang said: “This is the first time we have ever measured a wave of 19 metres. It is a remarkable record.
“It highlights the importance of meteorological and ocean observations and forecasts to ensure the safety of the global maritime industry and to protect the lives of crew and passengers on busy shipping lanes.
“We need high-quality and extensive ocean records to help in our understanding of weather/ocean interactions.
“Despite the huge strides in satellite technology, the sustained observations and data records from moored and drifting buoys and ships still play a major role in this respect.”
Experts say the highest waves typically occur in the North Atlantic, with wind circulation and atmospheric pressure in winter leading to extra-tropical storms often referred to as “bombs”.
The new record will be added to an archive that includes the world’s highest and lowest temperatures, rainfall, heaviest hailstone, longest dry period, maximum gust of wind and other climate extremes.
Randall Cerveny, joint rapporteur on world records of climate and weather extremes for WMO, said: “The new world record will be added to the official WMO archive of weather and climate extremes which is being constantly updated and expanded thanks to continued improvements in instrumentation, technology and analysis.
“Oceans cover some 70% of the world’s surface. Ocean observations are, therefore, critical to understanding and forecasting our weather and climate.”