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