FIFA published the finalised squads for each nation on Thursday, ending any doubt over Beikzadeh's involvement at the Brazil showpiece.
Iran had previously named a 24-man squad, with Mohammad Reza Khanzadeh on stand-by for coach Carlos Queiroz.
Argentina, Bosnia-Herzegovina and Nigeria await Iran in Group F at the World Cup.
Queiroz's men face the African nation in their first match, to be played in Curitiba on June 16.
Before that, though, is a friendly against Trinidad and Tobago on June 8 in Sao Paulo.
Squad in full:
Goalkeepers: Rahman Ahmadi (Sepahan FC), Daniel Davari (Eintracht Braunschweig), Alireza Haghighi (Sporting Covilha)
Defenders: Ahmad Alnameh (Naft Tehran FC), Steven Beitashour (Vancouver Whitecaps), Jalal Hosseini (Perspolis FC), Hossein Mahini (Perspolis FC), Pejman Montazeri (Umm Salal SC), Mehrdad Pooladi (Perspolis FC), Amirhossein Sadeghi (Esteghlal Tehran FC),
Midfielders: Hashem Beikzadeh (Esteghlal Tehran FC), Ashkan Dejagah (Fulham FC), Ghasem Hadadifar (Zob Ahan Isfahan FC), Reza Haghighi (Perspolis FC), Ehsan Haji Safi (Sepahan FC), Javad Nekounam (Kuwait SC), Bakhtiar Rahmani (Foolad Khuzestan FC), Andranik Timotian (Esteghlal Tehran FC)
Forwards: Karim Ansari Fard (Tractor Sazi Tabriz FC), Reza Ghoochannejad (Charlton Athletic), Khosro Heydari (Esteghlal Tehran), Alireza Jahan Bakhsh (NEC Nijmegen), Masoud Shojaei (UD Las Palmas)
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