Power joins the state-owned broadcaster from Westpac New Zealand, where he held multiple leadership positions, most recently as its interim chief executive.
The TVNZ appointment follows the resignation of chief executive Kevin Kenrick in September, after nine years at the helm.
TVNZ board chair Andy Coupe said Power was joining the company during a strong period of growth.
"This is an exciting time for a new leader to join the organisation, and Simon is focused on continuing this positive momentum as we accelerate our digital transformation, building an IP driven future for TVNZ and contributing to the Strong Public Media programme," Coupe said.
"Simon is passionate about the challenges and opportunities the organisation faces, and he joins a high-calibre executive team who are focused on delivering for viewers as their needs and the platforms they use continue to evolve."
Power said he was looking forward to joining TVNZ.
"I'm excited to have the opportunity to lead such an iconic organisation. The past year has truly demonstrated the importance a strong national broadcaster has in the daily lives of New Zealanders.
"I'm looking forward to joining the leadership team as TVNZ continues its digital expansion and moves into an innovative new era."
Before he joined Westpac, Power worked as a barrister and solicitor and spent 12 years as a member of parliament, holding ministerial portfolios for commerce, justice and state-owned enterprises while the National Party was in government.
Power will join TVNZ in March 2022.
He joins TVNZ at a time when the government is looking at a possible merger between RNZ and TVNZ. A decision is expected early in 2022.
