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