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