Cardiff and Vale health board says it's disappointed by the Welsh Government's decision to escalate intervention measures.
The authority is now facing the second highest level of targeted intervention from ministers amid concerns over its growing financial deficit, performance and workplace culture.
Up until now, the region's health board had been at Level 4 specifically over its finance, strategy and planning - but such measures will now apply to the whole organisation.
Health Secretary Jeremy Miles told Senedd members on Tuesday that a high number of so-called "never events" had caused "unnecessary harm and sometimes death".
He added: "It has the second largest number of people waiting more than two years for treatment and there have been a series of worrying cultural and leadership challenges which are indicative of an organisation which needs additional support."
Mr Miles added the health board's increasing financial deficit over the last 18 months meant it had breached its duty to agree a "three year balanced plan."
CAVUHB's chief executive said while the health board was disappointed by the move, it acknowledged "the status and factors contributing to it".
Suzanne Rankin said: "We are committed to working with colleagues and partners across the system to make the improvements required to achieve de-escalation and an established improvement trajectory."
"Ensuring patients who are waiting the longest can access timely care has, and remains, a priority and concerted efforts will continue. Addressing cultural issues is difficult but must be done."
"The work we are doing to ensure colleagues can speak up safely, and importantly, that their feedback is acted upon, has been underway for some time and will continue. Working on these elements together is essential to improving the safety of patients as well as colleagues."
"As ever, the key priorities remain the safety and quality of care provided to patients, colleagues and the communities of Cardiff and the Vale of Glamorgan."
"By working together in an efficient, productive and sustainable way, we know that sustained improvement leading to de-escalation is possible."
Last week, the health board confirmed the appointment of former education minister Kirsty Williams as its new chair.
The ex-Welsh Liberal Democrats leader will take up her role from October, succeeding Charles Janczewski, having served three years as vice chair of the Powys Teaching Health Board.
Williams was named as the health secretary's preferred candidate for the role last month ahead of a pre-appointment scrutiny hearing by the Senedd's health and social care committee.
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