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