Here is the full list of all 43 DARK SOULS III achievements. It takes around 80-100 hours to unlock all of the achievements on Windows.
Complete all achievements.
Learn all gestures.
Acquire all pyromancies.
Acquire all miracles.
Acquire all rings.
Acquire all sorceries.
Reach "The End of Fire" ending.
Reach "The Usurpation of Fire" ending.
Discover Mound-makers covenant.
Perform all forms of infusion.
Discover Aldrich Faithful covenant.
Discover Blade of the Darkmoon covenant.
Reinforce a bonfire to the highest level.
Reinforce the Estus Flask to the highest level.
Defeat Nameless King.
Reach "To Link the First Flame" ending.
Defeat Lothric, Younger Prince, Lord of Cinder.
Discover Rosaria's Fingers covenant.
Reinforce any weapon to the highest level.
Defeat Ancient Wyvern.
Reach Archdragon Peak.
Defeat Champion Gundyr.
Reach the Untended Graves.
Defeat Old Demon King.
Defeat Dragonslayer Armour.
Defeat Oceiros, the Consumed King.
Defeat Dancer of the Boreal Valley.
Defeat Aldrich, Devourer of Gods, Lord of Cinder.
Discover Way of Blue covenant.
Defeat Yhorm the Giant, Lord of Cinder.
Defeat Pontiff Sulyvahn.
Defeat High Lord Wolnir.
Defeat the Abyss Watchers, Lords of Cinder.
Discover Watchdogs of Farron covenant.
Defeat the Deacons of the Deep.
Defeat Crystal Sage.
Discover Blue Sentinels covenant.
Defeat the Curse-rotted Greatwood.
Discover Warrior of Sunlight covenant.
Defeat Vordt of the Boreal Valley.
Become a Host of Embers for the first time.
Defeat Iudex Gundyr.
Light a bonfire flame for the first time.