The British pair were the top seeds but they had to battle all the way to overcome the unseeded Danish pair of Anders Skaarup Rasmussen and Kim Astrup Sorensen 25-23, 16-21, 21-19 in a tense final.
Van Rietvelde and Ellis came from behind to win in the first game, recovering from 19-14 down. The Danes had four game points. The home favourites responded by taking the second game and they led 14-11 in the decider. But Van Rietvelde and Ellis produced a decisive run of points to move 17-14 ahead and went on to victory.
Van Rietvelde, from Longniddry, and Ellis are currently ranked No.35 in the world.