Here is the full list of all 47 Hitman: Absolution achievements. It takes around 40-50 hours to unlock all of the achievements on Windows.
You collected all 20 play styles
You completed Hitman: Absolution™ as a professional
You collected all evidence
You completed 100 challenges
You have defeated Sanchez with your bare hands
You played a contract made by a friend
You participated in a contract competition
You left Lenny in the desert
You earned 1 million contracts dollars
You performed 47 headshots using a sniper rifle
You achieved Silent Assassin
You eliminated Travis and fulfilled Diana's contract
You assassinated Blake Dexter
You assassinated Dexter's assistant, Layla
You visited Tommy the Tailor and acquired a new suit and gloves
You completed 50 challenges
You caught up with Skurky
You infiltrated the courthouse and accessed the jail
You created a contract competition
You liked a contract
You bought an upgrade for a weapon
You eliminated the Saints
You assassinated the facility leaders
You found your way through the mines
You circumvented Lenny's crew and secured Lenny
You re-gained your signature Silverballers
You questioned the bartender
You completed the Creating Contracts Tutorial
You completed the Contract Basics Tutorial
You assassinated Wade
You executed a point shooting with at least 3 kills
You assassinated Wade's men in Chinatown
You escaped the attention of an enemy
You boarded the train and escaped the Chicago PD
You made a kill look like an accident
You located the hotel room number 899
You blended in and fooled someone
You subdued a person
You completed 10 challenges
You unlocked a technique
You remained undetected throughout a checkpoint
You successfully performed a lethal throw
You fulfilled Birdie's contract and eliminated The King of Chinatown
You hid a body
You contained a situation gone bad
You infiltrated the mansion and assassinated Diana Burnwood
You ran the benchmark mode to see how well your hardware performs