Geason replaces Nerida Caesar, who took up Telstra CEO David Thodey's former post of group managing director for the enterprise and government group.
"It is important that Telstra Wholesale operates in a transparent manner that gives comfort to our wholesale customers that they are being treated on the same basis as our retail units in terms of price and service," Thodey said.
"Paul is an executive who I am sure will maintain his focus on meeting the needs and expectations of our wholesale customers."
Thodey also thanked Glenn Osborne, who has been acting in the role for the past month.
Osborne will return to his position as executive director for Telstra Wholesale sales.
Geason was with Telstra between 1994 and 2005, holding positions in Telstra's legal division and product management teams.
He left briefly to work for a US software company before rejoining the carrier in 2006.