An unqualified opinion is an audit report that has been issued with no reservations regarding the state of an audit client's financial statements. In this opinion, the auditor follows a standard opinion format to state that the financial statements are a fair representation of the financial results and condition of a client, in accordance with the applicable accounting framework (such as GAAP).
Creditors, lenders, and investors want to see financial statements with an unqualified opinion attached to them before they will lend money or invest funds. If there is any form of qualification to an audit opinion, this is a major red flag for financial statement users.
An unqualified opinion is also known as a clean opinion.