Huntelaar, who has become surplus to requirements at Real following the Spanish club's massive spending spree, will join Milan on a four-year contract, the Serie A club said on Thursday.
"The Dutch footballer will undergo medical checks tomorrow after which he will sign a contract that will bind him to the club until June 30, 2013," read a statement on the club website.
According to media reports, Milan have agreed to pay Real 15 million euros for the forward, who only joined them in January, for an inital fee of 20 million euros, after a prolific stint at Ajax.
He is no longer needed at the Bernabeu following the arrival of players such as Karim Benzema, Cristiano Ronaldo and Kaka.
Huntelaar, who turns 26 next week, will be Milan's first major investment so far in the close season.
The club will be hoping his arrival will allay fan unrest about their inactivity on the transfer market after they sold Brazil playmaker Kaka to Real for around 68 million euros.
The announcement comes a day after Milan owner Silvio Berlusconi said funds would be found for a "great goalscorer" and that Chelsea target Andrea Pirlo was staying.
Until now, Milan's only significant reinforcements were American defender Oguchi Onyewu, a free signing from Standard Liege, and Brazilian Thiago Silva.
Silva moved from Fluminense in January but could not play the second half of last season because Milan already had their full quota of non-EU signings.
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