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