Rode spent the second half of last season on loan at Eintracht, making 20 appearances in all competitions.
And last season's Europa League semi-finalists have now sealed a permanent deal for the midfielder, with a €4 million transfer fee reported to have changed hands.
Rode spent four years in Frankfurt earlier in his career before joining Bayern Munich for a short spell in 2014.
"I've seen how strong Eintracht have become in the last six months," Rode told the club's official website. "I'm happy to remain a part of that."
The club’s hierarchy enthused about the signing of Rode, both for his on-field impact and his connection to the city.
“He improved our game significantly when he joined last January. He’s also a local lad, and we’ve always said we’ll try and bring players like that to the club.
“The fact we’ve been able to do that shows we’re taking the next step in our development.
Rode could miss the start of the new Bundesliga season as he is still recovering from a knee injury sustained in the Europa League last-four tie against Chelsea, but the club say he’s making ‘excellent progress’ in his rehabilitation.
Frankfurt had a disappointing finish to the 2018-19 season which promised much as they entered the final stages.
They were in fourth place in the Bundesliga with weeks to go in the season, a position which would have brought them Champions League football.
They won the first leg of their qualifier 2-1 away against Flora Tallinn of Estonia.
Their semi-final defeat by Chelsea in that competition last season snuffed out their hopes of making Europe’s premier club competition by that route, but their lead from the game against Flora will give them hope they can compete for entrance to the Champions League on two fronts again next season.