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