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