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