So far, 186 States Parties have joined the UN Convention against Corruption. This also includes the European Union.

The only UN member states that have not signed or ratified the
Convention are Andorra, Barbados (signatory), Eritrea, Monaco, North
Korea, Saint Kitts and Nevis, Saint Vincent and the Grenadines, San
Marino, Somalia, Suriname, Syria (signatory), and Tonga.
You can find a map of UNCAC ratification here: https://www.unodc.org/documents/treaties/UNCAC/Status-Map/UNCAC_Status_Map_Current.pdf

The list of all countries that have signed and ratified the UNCAC is available on the UNODC website: https://www.unodc.org/unodc/en/corruption/ratification-status.html
and on the UN treaties website:
https://treaties.un.org/Pages/ViewDetails.aspx?src=IND&mtdsg_no=XVIII-14&chapter=18&clang=_en