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