The Cameroon international completed a season-long loan move to the Hammers on Saturday, sealing a return to London after quitting Arsenal in 2012.
The 26-year-old midfielder has spent the last two seasons at the Nou Camp following his £15m move from the Gunners, playing 39 La Liga matches and winning the title in 2012-13.
Former Liverpool defender, Rigobert, made 24 Premier League appearances for the Hammers between 2000 and 2002 under Harry Redknapp after quitting the Merseyside outfit.
And Alex took to his Instagram account to post a picture with his famous cousin after being unveiled to the Hammers crowd at Upton Park before a 3-1 loss to Southampton.
“Family passion same club,” Song posted on Instagram.
On Saturday, the 26-year-old admitted that he is delighted to be back in the Premier League after his two-year spell in Spain.
“I’m very happy to be here and very happy to see the guys and the fans today and to start to do my job for West Ham United,” Song said.
“I think this is very important for me to be coming back to London to West Ham United, which is a club with ambition to build a new stadium and become a big club. I am very excited to be part of this project.
“For me, when I was in Spain, I always said that if I was to leave one day I would return to the Premier League.
“It was a very hard decision, because when you have options of a lot of clubs who are playing in the Champions League, but at the end of the day I chose West Ham because I wanted to come to the Premier League.
“This is a league which has given me a lot and I didn’t finish what I wanted to achieve here.”
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