Scheduled to be delivered in March 2015, the new drillship will cost around $620m excluding capitalised interest.
The drillship will be capable of operating in water depths of up to 12,000ft and drilling depths up to 40,000ft.
Pacific Drilling said the new vessel will support dual gradient drilling and will be capable of accommodating 200 people.
Pacific Drilling CEO Chris Beckett said: "The strong market for deepwater drilling, attractive construction cost, strength of relationships with our preferred vendors, and robust operating performance of our in-service rigs support the decision to invest in the further expansion of our fleet."
According to the company, funds for the construction of the new drillship will be arranged through a combination of cash flows from ongoing operations and long-term debt.
The company says its fleet of eight ultra-deepwater drillships will represent one of the youngest and most technologically advanced fleets in the world.
Pacific Drilling currently operates four drillships under customer contract, and has one drillship on order and three under construction at SHI, two of which are under customer contract.
Pacific Drilling signed a contract with Samsung Heavy Industries in 2008 for the construction of its first four drill ships.