The Gunners twice fought back to secure a point at Stamford Bridge despite David Luiz's first-half dismissal, and Martinelli's performance in particular caught the manager's eye.
Arteta, 37, told reporters after the game he was impressed with Martinelli's attitude considering the task he faced:
"To play in this stadium the way he has done with 10 men and against Azpilicueta, who in my opinion is one of the best defenders in the league, and he was going against him every single time, you need courage to do that.
"Then his energy. I wanted to take him off a few times because he looked knackered, he was cramping and next minute he's sprinting 60 yards again."
He also hailed record signing Nicolas Pepe and Alexandre Lacazette in the absence of suspended captain Pierre-Emerick Aubameyang, who returns after Monday's FA Cup fourth-round clash away to Bournemouth.
Jorginho and Cesar Azpilicueta twice put the Blues ahead in west London, but Martinelli's breakaway strike and Hector Bellerin's 87th-minute equaliser ensured Arsenal came away with a share of the spoils:
Martinelli, 18, has surpassed expectations at the Emirates Stadium this term after he joined from Brazilian club Ituano in the summer for only £6 million.
Arteta emphasised how close he came to withdrawing the South American after Arsenal went down to 10 men and ultimately reaped the rewards of his own bravery, per Goal's Charles Watts:
Martinelli scored on his full Premier League debut for Arsenal—a 3-1 win over West Ham United in December—and his second strike in as many top-flight games marked his name in their history books:
He opened Arsenal's account when they drew 1-1 at home to Sheffield United in a tense affair on Saturday, with Arteta's side having now drawn their last three games in a row.
The Athletic's Amy Lawrence echoed Arteta's praise for the player given the derby occasion:
Martinelli continues to boost his reputation in north London and is already emerging as something of a talisman under Arteta, one who may be difficult to drop when Aubameyang makes his return to the lineup.