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