The attacker, who awaited clearance, is thus set for his debut and begun training in earnest with the rest of the squad.
Sandjar, who is based in Hamburg, will be available for selection when Mumbai FC take on defending champions Churchill Brothers in Goa Saturday.
Atul Bagdamia, vice president, Mumbai FC, said: "It is a pleasure to have him (Sandjar) for the season. In the company of Amiri, we hope both produce similar efforts respectively as they did for their country in the SAFF Championship and help Mumbai FC's campaign this season. We look forward to him score as many goals and wish him the best."
Sandjar joins countryman defender Haroon Amiri in what is an Afghan-first at any club in the country. He also becomes the third Afghan player to ply his trade in the I-League after Amiri and former Churchill Bros striker Belal Arezou being the other.
He is also the fourth player, Mohammed Mashriqi (Bhawanipore SC) being the other, from the South Asian nation to play in India.
Sandjar, 21, was born in Kabul, before his family moved to Hamburg in Germany. He grew up playing football as a youngster and also represented local side SC Vier-und Marschlande in the Oberliga Hamburg for two seasons covering 52 matches.
The attacker who can also play as a winger has been a regular in the Afghanistan National team scoring eight goals in 18 appearances overall since 2011.
Sandjar also bagged a couple of goals in the recently concluded SAFF Championships in Kathmandu, Nepal scoring against the hosts in the semi-final and India in the final.
The 5'10" player, in fact, was at Mumbai FC's game against Dempo SC at the Balewadi Sports Complex, Pune even though he couldn't play. Having trained for a few days with team now, he hopes to hit the ground running and make his mark as soon as possible.
Sandjar's signing completes Mumbai FC's foreign quota, which includes Orok Essien and Ghanian Yusuf Yakubu.
--IANS (Posted on 04-10-2013)