"Thank you to the entire city of Los Angeles for welcoming a 21-year-old kid with open arms and making this town feel like home," Goff wrote.
The message comes after Goff spoke to the Los Angeles Times about the trade.
Goff thanked the Kroenke family, coaches, support staff, and teammates for his time with the Rams. Goff described "relentless support" from the fans through ups and downs, calling it an "honor to represent L.A."
Goff ended his message with a look ahead to his time with the Lions.
"I couldn't be more excited for this next chapter and am ready to attack this new opportunity that lies ahead," wrote Goff. "Detroit, here I come."
Goff's message serves as the closest thing yet to an official trade announcement from the Rams, as the deal can not be finalized until the start of the new league year in March.