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