The younger Khan is looking to follow in his sibling's footsteps in the professional ranks after a decent amateur career that was capped with a bronze medal in the flyweight division at the 2010 Commonwealth Games in Delhi.
He will get to do so under his brother's Super Fight Promotions banner, which boasts long-time promoter Dennis Hobson as a partner.
"I've always wanted to turn professional and to do so under Super Fight Promotions was an opportunity that I couldn't turn down," said Haroon.
"I have big ambitions but will take things a step at a time and I know I've got the best team behind me, who have that experience, to help guide my career to the very top."
Tuesday's announcement comes just days after former IBF and WBA light-welterweight champion Khan revealed Virgil Hunter would be his new trainer, with his next bout against the undefeated Carlos Molina in December.
"I'm delighted that Haroon is the first fighter to sign for Super Fight Promotions. He's got a lot of talent and I know he can achieve a lot in the professional game," said the elder Khan.
"His amateur record will serve him well and I have no doubts that his decision to turn professional will prove to be a very fruitful one.
"Super Fight Promotions is a company which is going to make big waves in boxing as we actively seek to sign the very best young talent around."