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