The Cameroon international midfielder arrived at Upton Park from Barcelona last week on a season-long deal.
Tomkins believes that the 26-year-old's experience in the Premier League with Arsenal should help the Hammers enjoy a solid campaign in the top flight.
"Alex Song is a massive player who comes with great experience in the Premier League," he told the club's official website. "He has gone to Barcelona and trained with the best, so he is only going to help us, I should imagine. We're all really looking forward to playing alongside him."
Song could make his debut for West Ham on September 15 when they return to Premier League action at Hull City.