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