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