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