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