The victory shot them four points clear of rivals Barcelona, as the race for La Liga title enters the home stretch.
Madrid faced a stubborn, hard-tackling Getafe at the Alfredo di Stefano Stadium on Thursday.
It was a very edgy Madrid derby as the visitors frustrated their hosts. Notable was that the two teams shared evenly 10 yellow cards.
But captain Ramos secured a precious victory 11 minutes from time after Mathias Olivera was adjudged to have fouled Dani Carvajal.
Victory for Madrid who rested Eden Hazard, was their sixth in a row and they are strong favourites to dethrone stuttering Barcelona with five matches to play.