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