Portugal international midfielders Maniche and Costinha will leave Porto for Dinamo Moscow on 1 July in a massive coup for the Russian club.
Costinha and Maniche have been important players for Porto
Maniche, 27, is moving for 16 million euros (£11m), and 30-year-old Costinha for four million euros (£2.72m).
A statement on Porto's website read: "Porto have confirmed... the ceding of the sporting rights of Maniche and Costinha to Dinamo Moscow."
They were both losing finalists with Portugal in Euro 2004 last summer.
The duo also starred in Porto's victorious Champions League campaign of 2003/04 under Jose Mourinho, culminating in their 3-0 win over Monaco in the final.