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