The UNEX™ program has a large number of participating postal operators.
Currently, there are 36 postal operators participating in the UNEX™ programme (below in alphabetical order based on the ISO Code).
| Postal Operator | Country | Country Code ISO alpha-2 |
| Österreichische Post AG | Austria | AT |
| Australia Post | Australia | AU |
| bpost | Belgium | BE |
| Bulgarian Posts plc | Bulgaria | BG |
| Canada Post | Canada | CA |
| Post CH | Switzerland | CH |
| Cyprus Post | Cyprus | CY |
| Česká Pošta | Czechia | CZ |
| Deutsche Post DHL Group | Germany | DE |
| PostNord Danmark | Denmark | DK |
| Omniva | Estonia | EE |
| Correos | Spain | ES |
| Posti | Finland | FI |
| Le Groupe La Poste | France | FR |
| Royal Mail Group plc | United Kingdom | GB |
| Hellenic Post ELTA | Greece | GR |
| Croatian Post | Croatia | HR |
| Magyar Posta | Hungary | HU |
| An Post | Ireland | IE |
| Israel Postal Company Ltd. | Israel | IL |
| Iceland Post | Iceland | IS |
| Poste Italiane S.p.A. | Italy | IT |
| Lietuvos Paštas | Lithuania | LT |
| POST Luxembourg | Luxembourg | LU |
| Latvijas Pasts | Latvia | LV |
| MaltaPost | Malta | MT |
| PostNL | The Netherlands | NL |
| Posten Bring AS | Norway | NO |
| NZ Post | New Zealand | NZ |
| Poczta Polska | Poland | PL |
| CTT Portugal Post | Portugal | PT |
| Poşta Româna | Romania | RO |
| PostNord Sverige | Sweden | SE |
| Pošta Slovenije | Slovenia | SI |
| Slovenská Pošta | Slovakia | SK |
| United States Postal Service | USA | US |