The visitors grew into proceedings but it was the Magpies who deservedly led at the break, a lead they would double soon after thanks to Saint-Maximin.
The winger was sent through one-on-one with Ander Iruarrizaga in the Bilbao goal and coolly slotted home an effort into the bottom conrer.
The visitors responded through a Raul Garcia header after the hour mark and pressed for an equaliser but just couldn’t beat Martin Dubravka as the Newcastle defence stood tall.
The result made it back-to-back wins at home for the Magpies ahead of their season opener with Nottingham Forest.
Here are our Newcastle United player ratings from the clash with Athletic Bilbao at St James’s Park:
. NEWCASTLE UPON TYNE, ENGLAND - JULY 29: Newcastle manager Eddie Howe reacts on the sidelines during the Pre Season friendly match between Newcastle United and Atalanta at St James' Park on July 29, 2022 in Newcastle upon Tyne, England. (Photo by Stu Forster/Getty Images)
This is the Newcastle United team that will face Athletic Bilbao. (Photo by Stu Forster/Getty Images) Photo: Stu Forster
. Martin Dubravka - 7
Made a couple of decent saves including two to deny a rasping effort from Zarraga in the second-half. Photo: Stu Forster
. Emil Krafth - 7
Solid once again at right-back and dealt with everything with minimal fuss. Photo: Gualter Fatia
1. Martin Dubravka - 7
Made a couple of decent saves including two to deny a rasping effort from Zarraga in the second-half. Photo: Stu Forster
2. Emil Krafth - 7
Solid once again at right-back and dealt with everything with minimal fuss. Photo: Gualter Fatia
3. Jamaal Lascelles - 7
Looked solid alongside Botman and put in a strong claim to be named as a starter to face Nottingham Forest. Photo: Gualter Fatia
4. Sven Botman - 8
Looked assured at the back and was very confident on the ball when pressed by the Athletic attackers. Photo: Gualter Fatia