"The launch will be the most watched ever," said telecoms and media analyst Paolo Pescatore.
"Despite all the concerns surrounding Huawei, and the challenges it faces, it remains defiant and prepared to soldier on."
Washington effectively banned US firms from supplying Huawei in May, alleging the Chinese firm is a national security risk as its equipment could be used by Beijing to spy, which Huawei has repeatedly denied.
The No.2 smartphone maker expects the US ban to cost it $10 billion.
Huawei's new phone launch has been marked by uncertainty over whether buyers of the flagship Android device will be able to use apps supported by Google, a unit of Silicon Valley giant Alphabet.
Holding the launch in Europe underlines the importance of the region's 500 million consumers to Huawei. It lost five percentage points in market share here following the US ban, even as buyers rallied to its brand at home.
The Mate 30 range will run on an open-source version of Android - and not on the current version licensed from Google, a source familiar with the matter said.
The smartphones will not be able to use Google Mobile Services to use the Play Store and download apps like Gmail, Youtube or Maps. Instead, Huawei will offer its own interface that will allow users to access some Google apps.
Without those, say analysts, consumers won't want the phone - unless Huawei can find a way to convince them that its features are unmatched and the alternative software offering is stable and easy to use.
Huawei says the phone's 'brain' - the Kirin 990 chipset unveiled at a recent tech fair in Berlin - outperforms the Qualcomm-powered 5G phones already on the market from market leader Samsung.
In particular, the 'big core-tiny core' configuration of the hardware means it can run power-hungry applications like artificial intelligence or support online gaming, while saving battery on routine tasks.
The Mate 30 range's look and feel will be superior to Apple's new iPhone 11s, according to analyst Richard Windsor, who said leaked photos showed an attractive circular triple-camera set-up.
"Huawei has Apple soundly beaten when it comes to form factor design but even these beautiful-looking devices are going to struggle to see any volume without the Google ecosystem," Windsor said in a note.
Analysts are keen to learn when the phone will actually ship and how the pricing of the top-end Mate 30 Pro compares with Samsung's Galaxy S10 5G, which retails at $1,299, and the iPhone 11 Pro that starts at $999 but lacks 5G connectivity.
Huawei is expected to showcase the Mate 30 Pro, the Mate 30 and Mate 30 Lite - in line with its existing marketing strategy that targets buyers on different budgets. The phones would come in both 5G and 4G versions.