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