The result is a significant one for the Dragons as it is the first time since 2014 that they have beaten one of their Welsh rivals.
The home side were full value for their win as they held the lead for long periods and they eventually outscored the Ospreys by two tries to one.
For the Dragons Jared Rosser and Elliot Dee dotted down and their other points came courtesy of two penalties and two conversions from Josh Lewis, and Jason Tovey also added a penalty which proved to be the match-winning points.
Sam Davies’ boot kept the Ospreys in the match and he finished with a 17-point haul courtesy of five penalties and a conversion, and their other points came via a try from Justin Tipuric.
The home side’s interim head coach Ceri Jones will be delighted with his side’s performance especially the effort put in by his forwards, who shone in the tight exchanges.
Their scrum was particularly impressive and they also did well in the lineouts. Rosser’s try and Lewis’ goalkicking gave the Dragons a 13-6 lead at half-time but Davies kept the visitors in the game when he landed his third penalty early in the second half.
Dee then crossed for a converted try which extended his side’s lead and Tipuric kept the Ospreys in the game with his five-pointer with Davies adding the extras.
Another Davies penalty gave the visitors a 22-20 lead but Tovey sealed a memorable win for the Dragons when he slotted a place-kick in the 74th minute.