The 27-year-old defender played his first game of the season as the Gunners ran out comfortable 3-0 winners away to Eintracht Frankfurt in their opening Europa League fixture of the campaign.
Youngsters Joe Willock and Bukayo Saka stole the headlines as both academy products scored before Pierre-Emerick Aubameyang completed the victory with a late strike.
But Mustafi, much-maligned and told by head coach Unai Emery he was free to leave in the summer, played his part as Arsenal kept just their second clean sheet since April.
The Germany international has struggled to make an impact since moving to the Emirates Stadium in a big-money transfer in 2016 and was heavily linked with a departure.
Emery suggested after the European transfer window closed that it had been Mustafi’s decision not to leave and the former Valencia man is now ready to knuckle down and play when called upon.
“I’ve never been someone who begins a war when something doesn’t work out,” he said.
“I always said: If it is possible, I am open to take the next step. If not, I keep playing my football.
“My father, who is my agent, spoke to the club. I am an Arsenal player and still got two years contract.
“The manager said he sees me the same way he sees every player in the team. That’s why I played today and that’s it. We are going to see what the future holds.”
Speaking after an open game at the Commerzbank Arena where both sides wasted a plethora of chances and Frankfurt had midfielder Dominik Kohr sent off late on, Emery was full of praise for his young charges.
It was something of a vindication for the faith he has shown in Arsenal’s academy products since taking the head coach’s job last year and the Spaniard was delighted with both Willock and Saka – as well as Emile Smith Rowe.
“Their performance tonight was good and they deserve it,” he said.
“Maybe with his (Saka’s) goal, with his performance, but also in the match taking confidence, finishing really strongly physically.
“And also with Emile, after his injury tonight he played for the first time this season and he worked well. Willock also, progressively he was feeling better and with a good performance.”
Frankfurt manager Adi Hutter has had to deal with losing his three attacking talents, Luka Jovic, Ante Rebic and Sebastien Haller over the summer – the trio having scored 56 of the club’s 90 goals last season.
But, despite profligacy from new recruits Bas Dost and Andre Silva, the Austrian head coach was pleased with his side’s performance, if not the final result.
“It’s a bitter defeat for us,” he said.
“Because the performance does not reflect that result. When it was still 1-0 for Arsenal, we tried to score the equaliser but then conceded another one.
“The important thing is for us to create chances, I have seen enough of those. A goal can help open some doors, give you a boost, that did not happen today.”