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