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