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