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