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