The independent and publicly listed organisation was completed October 31, and Patriot Coal can now be found on the market ticker under PCX.
Peabody chairman Gregory Boyce said last month during the initial announcement that the decision to establish Patriot came after a review of the St Louis-based operator's assets and operations and will return maximum benefits to shareholders.
"Completing this spin-off was a key element in transforming our business portfolio," Boyce said on Thursday. "Peabody and Patriot will both benefit by a distinct business focus and growth opportunities."
Peabody, he added, will continue to stay focused on its "high-growth markets" including the Powder River Basin, Colorado and the Midwest as well as its global expansions.
Patriot president Richard Whiting concurred in an announcement of the company's public trading status.
"This is an exciting milestone for Patriot Coal and our dedicated employees and will allow greater management focus on our core mining operations," he said.
"As an independent company focused on creating shareholder value, we believe our broad asset portfolio will position us well to pursue effective long-term strategies and capitalise on market opportunities for both thermal and metallurgical coal."
The newly spun-off organisation will hold eight mines that are company-operated as well as two joint venture mines and several contractor-operated mines throughout the Appalachian and Illinois Basin regions.
In October, the companies said two of Peabody's board members, Irl Engelhardt and Bobby Brown, would move to Patriot.
The officials joined former vice-chairman of Emerson Electric J Joe Adorjan; former chief financial officer of Hanson Industries and Millennium Chemicals John Lushefski; senior vice-president and CFO of Bunge North America Michael Scharf; and former CEO and director of CILCORP Robert Viets.