The diplomat, a fan of the Hammers, believes Ayew’s reunion with his former Marseille pal Dimitri Payet will constitute a great threat to opponents in the Premier League.
Both players featured for the French giants between 2013 and 2015 in Ligue 1.
"I just spoke with Andre Ayew by phone in London and he can't wait to get stuck in for the Hammers," Benjamin tweeted.
"I go to bed happy, knowing that my man Andre Ayew is a Hammer. Now, here's quite a lethal pairing [Ayew and Dimitri Payet] reunited at West Ham to rip up the English Premier League this season. Be afraid, be very afraid! [I] can't wait for his first goal at the new stadium," he added.
Reacting to claims that he played a major role in Ayew's decision to join West Ham, Benjamin wrote: "I wish I had such influence! But, I'm very glad [that] Andre Ayew is now a Hammer. What a great signing!"
In his debut season in
England, Ayew won the league's Player of the Month of August, finishing the season as Swansea's top scorer with 12 goals.