Wally Downes has taken up a position as West Ham's defensive coach.
Assistant manager Zeljko Petrovic left his position earlier this week, and the Barclays Premier League bottom club have confirmed former Brentford boss Downes has now joined Avram Grant's backroom staff.
The 49-year-old, quoted in the London Evening Standard, said: "It is an honour to be asked to help out such a good club.
"I will do my best to help lift them out of the relegation area."
Downes worked under Steve Coppell during a successful spell at Reading, and was also at Southampton with ex-Irons boss Alan Pardew before the coaching staff departed in August.
Former West Ham striker and fans' favourite Paolo Di Canio has, meanwhile, been linked with a return to his old club in a coaching role.