Keinan joined on a free transfer after parting company with Maccabi Haifa.
He has agreed a one-year deal with an option for a further 12 months.
The 25-year-old had his work permit approved last month but only received it on Monday.
"I am looking forward to the first game and I'm very happy everything is done,” said Keinan. “"I had different offers but after I met the gaffer I was sure that I wanted to play for Blackpool.”
"I just want to play for Blackpool and help this team.”
He will be available for Blackpool's trip to Arsenal on Saturday.
