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.
Learn all gestures.
Acquire all miracles.
Acquire all pyromancies.
Acquire all sorceries.
Reach "The Usurpation of Fire" ending.
Perform all forms of infusion.
Reinforce the Estus Flask to the highest level.
Discover Watchdogs of Farron covenant.
Discover Mound-makers covenant.
Discover Rosaria's Fingers covenant.
Reach "To Link the First Flame" ending.
Defeat Lothric, Younger Prince, Lord of Cinder.
Discover Blade of the Darkmoon covenant.
Discover Aldrich Faithful covenant.
Reinforce a bonfire to the highest level.
Defeat Dragonslayer Armour.
Defeat Nameless King.
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 Dancer of the Boreal Valley.
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.
Defeat High Lord Wolnir.
Defeat Crystal Sage.
Defeat the Abyss Watchers, Lords of Cinder.
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.