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