Amy Adams has been appointed as National's finance spokesperson, ahead of the broader reshuffle of the party's caucus.
Ms Adams will also be ranked third in the caucus, behind party leader Simon Bridges and deputy Paula Bennett.
Mr Bridges said the MP for Selwyn was the best person to hold the government to account.
The appointment follows the announcement senior MP Steven Joyce, who had held the finance portfolio, would soon quit Parliament.
The government has inherited a fast growing economy, with thousands of jobs created each month, said Mr Bridges.
"However, the Labour-NZ First-Green coalition government seems intent on squandering that through plans to impose more taxes on hard-working New Zealanders and through rolling out negative and backward looking policies which will slow down our growth."
Ms Adams is a former Associate Finance Minister, and also held portfolios of Social Housing, Justice and Environment.
She has singled out Labour's overseas investment changes, employment law changes and proposed new taxes as threats to the New Zealand's economic performance.
"These changes are bad for all of us", said Ms Adams.
"Slower business growth means less investment, fewer job opportunities, and lower wages generally than would otherwise be the case."