Ben Arfa teed up 10-million-pound January signing Papiss Demba Cisse for United's first goal early at the Hawthorns, before scoring himself later as Newcastle eased to their 14th Premier League victory this season.
Ben Arfa, so often a frustrating figure since his arrival at St James' Park, also created Cisse's second goal in an exhilarating first-half performance as Newcastle went another three points closer to securing a top-six finish.
Manchester United moved three points clear at the top of the Premier League table after a 1-0 win over Fulham at Old Trafford.
United peppered the Fulham goal from the outset but did not manage to score until just before half-time through Wayne Rooney.
The game's only goal game four minutes before the interval when Ashley Young delivered a cross from the left, with Fulham's failed attempts at a clearance allowing Jonny Evans to cut back to Rooney for a close-range finish.
