The deal, in place, is pending physical examinations and likely will not be formalized until early next week.
The Padres have been shopping Kouzmanoff for the better part of a year because he's eligible for salary arbitration and they need to clear third base for Chase Headley, who played left field last year but is better suited for third base.
The deal comes after Kouzmanoff set a National League record for third basemen in 2009 with a .990 fielding percentage.
Oakland acquires not only a solid glove man -- Kouzmanoff finished second to Washington's Ryan Zimmerman in Gold Glove voting -- but a third baseman who can put the ball out of the park. Kouzmanoff last year hit 18 homers and collected 88 RBI while hitting .255 with a .302 on-base percentage. He's hit 41 home runs over the past two seasons.
While looking to make room for Headley and clear Kouzmanoff's salary, the Padres had been looking for a right-handed hitter who can split time in center field with Tony Gwynn Jr.
In re-acquiring Hairston, who played in San Diego from 2007-2009 until former general manager Kevin Towers traded him to the Athletics last summer, the Padres obtained exactly what they were looking for.