Campbell was named in the starting line-up for West Brom's 3-0 win over Arsenal, with the Gunners' official website confirming it was indeed the Newcastle United forward.
The forward played an hour in the victory, and provided the pass for strike partner Adil Nabi to net his second of the game early in the second half.
Campbell's future at Newcastle is officially undetermined, with his contract set to expire at the end of the current season.
The fact the 20-year-old was permitted to go on trial suggests he does not have a future at the club, and is likely to be released imminently.
Campbell has represented England at under-16, under-17, and under-19 levels, and has made a total of five first team appearances for Newcastle United, twice in the Europa League and three times in the Premier League, but they all came last season.
He has 12 goals and eight assists in 30 under-21 games to his name for Newcastle, and was named on the bench for the FA Cup loss to Leicester earlier this year.