Timber has not played since sustaining a groin injury during a Premier League win over Everton on March 14 and his absence had created a selection problem at right-back, with Ben White ruled out by a knee ligament injury. Madueke came off during Arsenal's final league fixture at Crystal Palace the previous weekend with what appeared to be a hamstring problem.
Arteta was unambiguous when addressing both players' availability on Friday evening.
"Timber is fit. Fit enough to start? Yeah. Madueke? Yeah, he is fit. The only one is Ben."
The Arsenal manager also rejected the suggestion that winning the Premier League title has taken the pressure off his squad going into the final. His reply was direct.
"No. The ambition is bigger. We have one and we want the second one. That is all we have been talking about. There has to be a platform to reach bigger destinations and to aim for more."
He described the club's Champions League campaign as evidence that his side belong at this level.
"The team is capable because they have shown it in the last seasons in this competition and what we have done this season in the competition. I want the players to be so confident that we are going to go and do it."
Arsenal are pursuing a first ever European Cup, having last appeared in the final in 2006 when they lost 2-1 to Barcelona in Paris. PSG won the title last season and are attempting to become only the second club to retain it in the competition's modern era.
Arteta framed the challenge without attempting to downplay it: "They are defending the trophy and they are the champions and we are here to take that away from them."
The only senior absentee is White, whose knee ligament injury ended his season earlier this month. Timber's return provides the natural right-back option Arteta had been building his defensive structure around before the injury setback in March.