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