The Argentine has been on loan at the Championship club for the past month.
The 22-year-old has had to step up and be counted for Arsenal this season when injuries struck both David Ospina and Wojciech Szczesny in November and December.
He has played six times for Arsenal this season and kept three clean sheets, performing well under immense pressure for one so young.
He is prone to the odd error, but that may iron out with age and Martinez will certainly have his eyes on a first-team place at Arsenal in the not so distant future.
The Argentine goalie has now spent the past month on loan at Rotherham United of the Championship, impressing in his seven games at the club.
Last night the goalie, who spent last term on loan at Sheffield Wednesday, helped The Millers secure safety in the Championship for next season as they defeated Reading at the New York Stadium - sending Millwall and Wigan Athletic to League Two along with basement club Blackpool.
After the win he sent out these Tweets, showing his appreciation for his current club and his joy at securing their survival.
Determination,hard work,believe proud of this Football club #Millers#Championship https://t.co/MNXMeFtCRj— Damian Emi Martinez (@emimartinezz1) April 29, 2015
His loan deal in Yorkshire will end after the weekend and he will be hoping to come back to Arsenal and push on for a first-team place, or get another term playing regularly on loan under his belt in 2015-16.