Williams took to social media to celebrate his graduation from Otago Polytechnic where he earned a Bachelor of Applied Management (Sport Management) with distinction.
The 33-year-old posted a picture of his new degree alongside another of him in his graduation gown surrounded by his family.
"Yes a Pacific Islander, boxer, league, sevens & rugby player can GRADUATE!" he said in the post.
"Don't ever let anyone pigeon hole you. Alhamdulillah."