Here is the full list of all 37 Thief achievements. It takes around 40-50 hours to unlock all of the achievements on Windows.
Discovered all secret areas
Finished the game with a custom difficulty of 700 points or more
Reached the final chapter without using the focus ability
Finished the game on Master difficulty
Completed 25 optional Thieving Objectives
Used 40,000 gold
Finished the game without a single kill or knockout
Scored an epic 5,000,000 or more in a Challenge Map
Completed all collectible sets
Picked 100 pockets in a single playthrough
Completed 10 optional Thieving Objectives
Finished 3 consecutive chapters without taking damage
Finished the game in 15 hours or more
Completed all Basso Jobs in The City
Completed all client jobs in The City
Completed a collectible set
Found all the secret stashes in Moira
Disarmed ten trap mechanisms
Picked a pocket and a lock using the focus ability
Discovered 15 secret areas
Shot a bottle in mid-air with an arrow
Killed or knocked out 10 people using the environment
Stole all loot and collectibles in a single chapter.
Uncovered Lyegrove's secret
Finished a single chapter without alerting anyone
Finished Chapter Eight
Finished Chapter Seven
Finished Chapter Six
Finished Chapter Five
Finished Chapter Four
Finished Chapter Three
Sweet sixteen. Snuff said.
Picked a lock with masterful speed
Finished Chapter Two
Stole 5 collectibles
Finished Chapter One
Finished the Prologue