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.
Reach "The Usurpation of Fire" ending.
Discover Rosaria's Fingers covenant.
Reinforce a bonfire to the highest level.
Reach "The End of Fire" ending.
Defeat Nameless King.
Discover Aldrich Faithful covenant.
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.
Defeat Dragonslayer Armour.
Reinforce any weapon to the highest level.
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.
Defeat Pontiff Sulyvahn.
Defeat High Lord Wolnir.
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.
Complete all achievements.
Reach "To Link the First Flame" ending.
Perform all forms of infusion.
Acquire all sorceries.
Acquire all pyromancies.
Acquire all miracles.
Acquire all rings.
Learn all gestures.