The Rossoneri boss believes the Ghanaian's signing could be a pivotal starting point as he rebuilds the squad, while he insists missing out on Europe would not be "shameful"
Essien is expected to be confirmed as a Rossoneri player in the coming days after a deal was agreed with Chelsea, with the 31-year-old making only five Premier League appearances for the Blues this season.
Speaking ahead of his side's clash with Cagliari on Sunday, Seedorf enthused about the "warrior" Ghanaian's ability and claimed he will form an integral part of his attempts to turn the club's fortunes.
"I know Essien quite well," the 37-year-old Dutchman told journalists at a press conference.
"I spoke with him clearly and transparently. We know him as a player and he's a very big positive for us. He'll be a big help.
"I'm happy with Essien's arrival. He'll play in the middle - he can also operate as a full-back but I always like to see players in their best position.
"Maybe it's a good thing [if he's had a sceptical welcome]. If you look at the benches of Real Madrid and Chelsea, there are some great players who are maybe surplus to requirements. I have guarantees regarding Essien. He's a warrior with a lot of experience."
Milan have endured a torrid campaign so far and sit 11th in the Serie A table, and Seedorf has conceded that Champions League football may well be beyond his side for next season - though he insists this would not be "shameful" for the club.
"The objective at the moment is to us all our determination to improve results," he continued.
"Work and commitment will get us there. I'm here to help with this reconstruction but it's clear that we need time and as things stand I can't set a date for when the results will start to come.
"Commitment is what's needed and I can see that with the players. They're the first to understand the fans and the most disappointed to be in this situation. This has happened to other big clubs that have fought their way back, however. I'm here to work to do that and to make the fans dream again.
"A season without Champions League football is not the end of the world, it's happened to many big clubs and it's not shameful. You have to accept the present, otherwise you're living an illusion."