Kanu urged his fellow Nigerian to make the switch to Upton Park.
Obinna revealed to whufc.com: "I spoke to the Legend, as we call him in Nigeria for advice. [Portsmouth striker] Kanu is the king. He said many good things.
"He was so excited for me to come here. He gave me some advice before signing for West Ham and told me to go for it. He encouraged me. He has played under the manager and said they had a very positive relationship."