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