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