Ms Denholm has been a senior executive at Juniper Networks for nearly 10 years and was most recently chief financial officer and chief operations officer. Juniper operates and manages global network equipment and software security.

She is also a director of Tesla Motors and Zurich-based robotics and technology company ABB.

Telstra chief executive Andrew Penn said the company had made a "world class appointment to oversee the next generation development of its operational environment". Ms Denholm will oversee up to $15 billion of capital expenditure over the next three years.

Telstra shares were down 5 cents at $4.90 in trading on Monday afternoon.

"Robyn has a proven track record as a global COO in a business focused on telecommunications networks. She has overseen business model transformation, supply chain and broader business process re-engineering," Mr Penn said.

She is credited with a big increase in Juniper's revenues and restructuring the company between 2014 and 2015.

Also an accountant, Ms Denholm has been based in the US since 2001 but was born and educated in Australia. She will return to Sydney to work at Telstra and is expected to start her new role in early 2017.

She was previously senior vice-president of corporate strategic planning at Sun Microsystems, and has worked for Toyota and Arthur Anderson.

The Australian Graduate School of Management at UNSW offers a Women in Technology scholarship named after Ms Denholm.

Brendon Riley has been acting in the role since Ms McKenzie resigned in July, following a series of network outages that left Telstra embarrassed.

Mr Riley will return to his role as group executive global enterprise and services.