The aggregate rating of Celebrity Millennium is build on scorse given by the following portals:
| Aug / 24 | Sep / 24 | Oct / 24 | ||
| cruisetimetables.com | 3.0 / 73 | 3.5 / 73 | 3.4 / 61 | |
| seascanner.com | 8.4 / 23 | 8.2 / 27 | 8.2 / 28 | |
| cruisemapper.com | 4.0 / 1 | 4.0 / 1 | 4.0 / 1 | |
| cruiseline.com | 4.1 / 1129 | 4.1 / 1131 | 4.1 / 1134 | |
| cleancruising.com.au | 4.4 / 42 | 4.4 / 44 | 4.4 / 45 | |
| cruisedirect.com | 4.2 / 20 | 4.2 / 20 | 4.2 / 20 | |
| cruisecritic.com | 3.7 / 1 | 3.7 / 1 | 3.7 / |
Celebrity Millennium is also ranked in:
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