The struggling Premiership club have only Michael Oakes available as a result of Matt Murray's long-term injury problems and are on the look-out for a new custodian after their first choice target, Paul Jones, joined Liverpool last week.
The former Liverpool shot-stopper has been in fine form for The Lions this season and was voted the club's Player of the Year last season.
Millwall have put a price tag of £1 million on Warner but Wolve's boss Dave Jones may have no option if he wants to strengthen his squad ahead of their relegation fight.