Pogatetz previously spent five years in England with Middlesbrough before moving to the Bundesliga to join Hannover in 2010.
He left Hannover for Wolfsburg on a three-year contract last summer, but is now poised for a return to the Premier League.
The Austrian is understood to have arrived in England on Sunday night and will have a medical on Monday before finalising his switch to Upton Park.
The 30-year-old's anticipated arrival at West Ham will be a major boost for manager Sam Allardyce, who has been desperate to strengthen his defensive options throughout January.
Allardyce has also been linked with a move for Aston Villa's Stephen Warnock, with left-back a particular area that the Hammers boss has been keen to improve.