Update on February 8: Capcom announced on Friday that the Monster Hunter: World game has shipped 12 million copies worldwide (the number includes digital sales) as of January 23. Source: 4Gamer

ANN's original article is below.

Capcom revealed on Monday in its third quarter financial report for fiscal year 2018 that the Monster Hunter: World game has shipped more than 11 million copies worldwide. The figure includes digital sales and the PC release. Capcom launched the game for PC on August 9, and the report credits the PC release as providing a boost to the game's sales. The third quarter ended on December 31.

Monster Hunter: World launched worldwide on PlayStation 4 and Xbox One on January 26, 2018 and shipped 5 million copies worldwide (including digital sales) in its first three days to set a new franchise record. The number reached 8.3 million copies in July. The game shipped 10 million copies to become the best-selling title in Capcom's history as of August 20. The Monster Hunter series has cumulatively shipped 50 million copies worldwide as of August 20.

The game will get an expansion titled Monster Hunter World: Iceborne in fall 2019. The expansion will feature a new story that begins after the events of the main game, as well as new quest ranks, locales, monsters, moves, and equipment.

Source: Capcom's 3rd Quarter Report via Siliconera (link 2)