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