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