The 27-year-old German has joined Esteghlal for the 13 remaining games in the Iranian Professional League (IPL) for an undisclosed fee.
Helmke began his professional career with VfL Maschen.
Helmke has also played in German clubs Lüneburger SK and VfB Lübeck, Malaysian Sabah FA, and Finland’s FF Jaro.
After a spell with Jaro, Helmke joined the Norwegian Tippeligaen side Tromsø on a free transfer in August 2013 and signed a two-and-a-half-year contract with the club.