The 23-year-old Serbia striker, who joined Real in June 2019 in a transfer worth around 60 million euros ($72 million), has been loaned back to Frankfurt for the rest of the season.
Despite netting just twice in 32 appearances for Real, Jovic showed superb finishing for his first goal on Sunday just 10 minutes after coming on.
"It was like a script from a Hollywood film," said Frankfurt director Fredi Bobic.
It was his first game for two months after contracting Covid-19 in November, followed by injury, but Jovic then struck again just before the final whistle in Frankfurt with another clinical strike.
Portugal striker Andre Silva put Frankfurt ahead before US teen Matthew Hoppe, who last weekend became the first American to score a Bundesliga hat-trick, equalised for Schalke.
However, the Royal Blues are again last in the table because of Mainz's 1-1 draw at Dortmund on Sunday (AEDT).