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