Albion ended last season by beating Portsmouth in front of their own fans to avoid relegation from the Premiership.
In that game, Horsfield made one goal and scored another and he again showed his liking for playing against Pompey with a strike in each half to secure an impressive win for Bryan Robson's side.
Albion were well in control and cruising when Portsmouth were given hope by a trademark Laurent Robert free-kick.
But even the heroics of Robert were not enough to save a new-look Pompey side who have started the season with back to back defeats.
In sharp contrast, Albion have collected a useful four-point haul from their opening two games to give them a boost as they head into Wednesday's daunting test at Chelsea.
Portsmouth had no answer to the determination of Horsfield who had not even been in the 16 for Albion's opening day draw at Manchester City.
But, with new £3million striker Nathan Ellington sitting on the bench after his arrival from Wigan, the former Birmingham City marksman grabbed his chance to impress with both hands.
Horsfield ghosted in at the far post to head Albion in front with a neat piece of finishing after just two minutes.
He capitalised on good work on the left wing between Paul Robinson and Jonathan Greening.
Greening whipped over a perfectly placed cross that picked out Horsfield to nod the ball past the Portsmouth goalkeeper Sander Westerveld.
From Portsmouth's point of view, it was a bad goal to concede as Horsfield was able to get in between Dejan Stefanovic and Andy O'Brien to head the ball home.
It was a setback that Portsmouth struggled to get to grips with and it was not until the final ten minutes of the first half that they began to test Albion.
Referee Mike Riley waved away their appeals for a penalty in the 13th minute after Lomano LuaLua had gone down under a challenge from Thomas Gaardsoe.
It was Albion who continued to pose the greater threat in attack and Horsfield was close to grabbing his, and Albion's second, after 22 minutes when he turned a right-wing cross from Zoltan Gera over the bar.
That lucky escape finally sparked Portsmouth into life as the lively LuaLua went on a one-man mission to try and haul them back on to level terms.
Twice he flashed shots across the face of the goal as Albion struggled to cope with the pace of the former Newcastle United marksman.
But the inability of LuaLua to convert the chances that came his way was to prove costly for Portsmouth as Horsfield sealed an impressive Albion success on the hour.
This time it was Gera who created the goal when he cut into the area and fed Horsfield.
Westerveld seemed to have the shot covered but somehow the former Liverpool keeper allowed the ball to trickle under his hand and roll just over the goal-line.
It should have been the signal for Albion to cruise to victory but Portsmouth ensured they would have to battle all the way for their first three points of the season when Robert produced another stunning goal from a free-kick three minutes later
The Frenchman gave Albion goalkeeper Chris Kirkland no chance when he curled the ball around the wall from 20 yards but it proved to be scant consolation for Portsmouth.
Man of the Match: Geoff Horsfield - The Albion forward responded to the arrival of new striker Nathan Ellington in style with a masterful display to boost his claims for a run in the side.