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.
Acquire all miracles.
Acquire all pyromancies.
Acquire all sorceries.
Reach "The Usurpation of Fire" ending.
Defeat Nameless King.
Reinforce any weapon to the highest level.
Perform all forms of infusion.
Discover Blade of the Darkmoon covenant.
Reinforce the Estus Flask to the highest level.
Discover Mound-makers covenant.
Reach "To Link the First Flame" ending.
Defeat Lothric, Younger Prince, Lord of Cinder.
Reinforce a bonfire to the highest level.
Defeat Dragonslayer Armour.
Defeat Ancient Wyvern.
Reach Archdragon Peak.
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 Aldrich Faithful covenant.
Defeat Pontiff Sulyvahn.
Defeat Old Demon King.
Discover Watchdogs of Farron covenant.
Discover Rosaria's Fingers covenant.
Defeat High Lord Wolnir.
Defeat the Abyss Watchers, Lords of Cinder.
Defeat the Deacons of the Deep.
Defeat Crystal Sage.
Discover Blue Sentinels covenant.
Discover Warrior of Sunlight 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.