Sunderland boxer to fight on the undercard of Anthony Joshua vs Daniel Dubious
The massive card takes place at Wembley in September.
Josh Kelly: "Firstly, I want to His Excellency, Riyadh Season and Spencer Brown, a big thank-you.
"I'm a big 154 fighter so 160 will suit me. I have nothing but respect for Liam, he has had a great career, he put Liverpool on the map - him and his brothers - and there is no bad blood between us, it's just business
"Stylistically it's one of the best match-ups on the card."
Kalle Sauerland, Head of Global Boxing at Wasserman, said: "Yet again, the Riyadh Season, the global takeover, delivers. We've just got our breath back from the Undisputed clash and 5 vs 5, and now this, a historic card, the best card ever in Britain.
"The main event is absolutely gigantic, but Kelly vs Smith, could steal the show. Yes, it is the right time to fight Liam, at the right weight. People who are around the scene, know of Josh Kelly's potential and this is his time to shine, in front of 90,000 people at an iconic venue.
"But it's not about this being the right time to fight Liam, it's Josh's time. Adam Booth has done a fantastic job, this man is on fire. I believe this fight will steak the show."
Liam Smith said: "This is a great fight on a huge card. It's a fight that not many people thought about but now it's announced, they can see it's an interesting fight.
"My focus is on Josh Kelly; I am massively confident of winning. Josh and Adam probably feel like they are getting me at right time. Fighters have made that mistake before, and they are doing the same thing.
"Josh has got to step up at some point and this might be his right time, but people have thought they are getting me at the right before - Anthony Fowler did so after I fought in Russia. I feel refreshed now, we have long enough to go, this has lit the fire in my belly. Big respect for Josh and Adam, but business is business."