The Dutchman touched down in Lombardy and headed straight for San Siro, arriving midway through the second half of Milan's Coppa Italia clash with Spezia - with the score at 3-0 to the hosts.
Seedorf was warmly greeted by Milan chief executive Adriano Galliani as he took his place in the stands, with supporters in attendance also welcoming him back.
"I'm back? The truth is I never went away," Seedorf told reporters at Milan's Linate airport.
"There is a lot of work to do in order to bring Milan back to the top.
"President Silvio Berlusconi had predicted everything two years ago. I am very touched and very, very happy. The team and the fans need this enthusiasm."
Seedorf is expected to be officially announced as Milan coach after announcing his retirement from football on Tuesday to take the role.
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