Solano passed a medical at St James' Park on Wednesday evening and the deal was completed with less than an hour of the transfer window remaining.
Despite what Freddy Shepherd said this afternoon, Newcastle have agreed to allow Milner to join Villa on a season-long loan. Milner made his breakthrough at Leeds United during current Villa manager David O'Leary's tenure at Elland Road.
The England Under-21 international has now been reunited with O'Leary and will hope for regular first-team football at Villa Park.