The Albion starlet signed a new three-and-a-half year deal on Monday to take his pay from £850 a week to £15,000 a week.
"Now it is sorted I can't wait to keep going," said Berahino, whose heroics included the winner in an away victory over champions Manchester United.
"My aim is to make an impression on the Premier League, help the team and improve as a player and see where it takes me. Hopefully I can only become a better player.
"I was here since I was 11 and I'm so happy to be here and want to thank everyone who has helped me, the gaffer for allowing me to express myself and hopefully it will continue.
"Steve Clarke has been brilliant, he has given me a platform to perform and allowed me to fit in with the lads, I can't thank him enough for giving me the opportunity on the big stage."
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