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