Curtis Wilson led the way with a hat-trick – his first tries of the season – and Tom James, Nick Civetta and Steve McColl also crossed in Knights’ five-point win.
A try by Miles Mantella gave Scottish an early lead before James finished off a super move involving Cameron Cowell and Josh Tyrell.
Mantella went over for his second try, but McColl raced clear from an interception on half-way and Kurt Morath’s second conversion made it 14-10 to the visitors.
London Scottish went ahead for the third time through Joe Luca-Smith, but Nick Civetta drove over and then Wilson raced in for a long-range try from Morath’s pass to make it 24-15 at half-time.
Smith’s second try soon after the break gave Scottish hope, but Wilson pounced on a fine cross-kick by Morath for a converted try which opened an 11-point gap.
Doncaster were reduced to 14 players when Cameron Cowell was sin-binned at the end of the third quarter, but Wilson’s third try – created by James and Morath – sealed a magnificent win for the South Yorkshire side.
Doncaster are now just a point below Scottish with 17 points from nine games and are in ninth place.
London Scottish: Smith, Mantella, Williams (Duncan 64), Vernon, Stevenson, Perry, Hart (Frost 49), Dawe Saunders, Palframan (Cringle 63), Hodge, Uanivi, Tyas, Wynne, Bright.
Doncaster Knights: Cowell, Wilson, Hayes, Creed, McColl, Morath, James (Seniloli 79), Hislop (List 67), Hunter ( Malcolm 70), Quigley (Sproston 62), Challinor (Eames 67), Civetta, Ryan, Hills (Booth 79), Tyrell.