The young attacker was signed by City over the summer and loaned back to River for the season.
City were planning to place Echeverri at LaLiga partners Girona, but they will now add the youngster to manager Pep Guardiola's injury-hit squad.
“I wanted to thank you for the support I have always had since I was a kid, in the club where my videos began to be known, I wanted to thank you for the affection with me and my family, grateful to River, with you, with the club, the people who work at the club," he said after his final game for River.
“It’s something unique, very nice to be here, to play for River when I was so young, at the age of 17, when I was lucky enough to make my debut. Thank you for always being with us, the stadium is full every game and I hope I can return soon.
“Today I have to say goodbye to the club of my life, the one I joined at a very young age with a lot of dreams to fulfil. River became my second home, the club that formed me not only as a professional but also as a person.
"I want to thank the fans, teammates, coaching staff, leaders and people who work at the club for all these years. Also, to my family and friends, none of this would have been the same without them.
“I’m going to miss them and I’m going to continue being another fan wherever I have to be. Thank you from the bottom of my heart and see you soon.”