Fisher, 32, joined the Broncos as assistant coach at the end of last season, but was registered as a player with the RFL.
Coach Tony Rea said: “It was always part of our plans, it was an option from day one. He’s looked sharp in training this week.”
Meanwhile, Sam Tomkins remains a doubt for Wigan although he is included in their 19-man squad.
Wigan 19-man squad: Burke, Charnley, Crosby, Dudson, Farrell, Flower, Green, Hughes, McIlorum, Mossop, O’Loughlin, Powell, Richards, Smith, Taylor, Thornley, L Tomkins, S Tomkins, Tuson.
London 19-man squad: Bailey, Bryant, Channing, Cook, Colbon, Dixon, Dorn, Fisher, Gower, Kaufusi, Krasniqi, Lee, Melling, Randall, Rodney, Sarginson, Wheeldon, Witt, Lovell.
Prediction: It’s hard to see London picking up their first win of the season at the DW Stadium – home win.
Wigan have won their last five meetings with London Broncos/Harlequins (two at home), with the capital side’s last win coming 38-26 at the DW Stadium on 23 April, 2010.
Super League summary: