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