The Magpies have won both of their pre-season games so far, but this should prove to be a step up for Eddie Howe's men.
Newcastle thrashed Gateshead 5-1 before a strong second-half performance with goals from Joe Willock, Sean Longstaff and Bruno Guimaraes sealed a win against 1860 Munich.
But this game has been marred by complaints from a section of Mainz fans, who wanted the match to be cancelled due to the Magpies' connections with Saudi Arabia.
The German club refused to postpone the fixture, however, it's been suggested there could be protests at the match.
After two easier matches, this will be a good opportunity for Howe to assess exactly where his side are ahead of the 2022/23 season.
Newcastle v Mainz: Date and start time
This pre-season friendly will take place on Monday, July 18.
Kick-off at the Kufstein Arena will be at 3pm UK time.
Newcastle will next travel to Portugal after their final clash in Austria to take on Benfica with the Eusebio Cup up for grabs.
Newcastle v Mainz: TV channel and live stream
Newcastle fans can watch this game free of charge.
The Tyneside club confirmed the friendly will be broadcast live via their official YouTube channel and via NUFC TV.
talkSPORT will have regular updates throughout the day while talkSPORT.com will be on hand for all the post-match reaction.
To tune in to talkSPORT or talkSPORT 2 through the website, click HERE for the live stream. You can also listen via the talkSPORT app, on DAB digital radio, through your smart speaker and on 1089 or 1053 AM.
Newcastle v Mainz: Team news
Jamal Lewis, Matt Ritchie, Javier Manquillo and Federico Fernandez all missed the win over 1860 Munich.
Lewis and Ritchie both picked up knocks, so were rested as a precaution, while Manquillo is currently in Spain dealing with an injury.
And Fernandez was absent from training on Sunday morning.
Howe might also decide to start Guimaraes, Sven Botman and Kieran Trippier after all three started the 1860 Munich match on the bench.
Young starlet Elliott Anderson could also get another chance to shine and seal a spot in the first team ahead of the new campaign.
Newcastle v Mainz: What has been said?
Howe on the transfer market: "There is nothing to report and we're still in the process of working very hard behind the scenes to try and improve the squad.
"We are keen to add strength to certain areas of the team. It remains to be seen whether we can get a deal done. It is a difficult window, a difficult market, high prices and very limited availability. I'm sure we can hopefully a land a player who can make a difference to us.
"You have to be adaptable because if we can't find the right player, I might have to look at other positions. We are looking at quality players who will make the group better, regardless of position."