Strikes from Danny Hollands, Anton Robinson and Marc Pugh turned the match around after Sean O’Hanlon had headed MK Dons in front two minutes before half-time.
Peter Leven cut the deficit from the penalty spot 10 minutes from the end, but the Cherries held on for the victory.
MK Dons had lost their previous four away matches, but produced a disciplined first-half performance and took the lead just before the break when O’Hanlon buried a far post header past Shwan Jalal from Leven’s corner.
Bournemouth threw the talismanic Steve Fletcher into the fray shortly after half-time and he seemed to energise Bournemouth, who promptly scored three times.
Hollands deflected Pugh’s low free-kick into the corner for the equaliser before the unmarked Robinson made it 2-1 from a corner. A superb glancing header from Pugh gave Bournemouth breathing space before Leven pulled a goal back from the spot after Hollands fouled Mathias Doumbe.