The group – known for its unique cooking method of ‘smashing’ beef on to a hot buttered grill – launched its debut site in Milton Keynes on 25 May.
It is also planning to open in the former Mucho Burrito site on Brighton’s North street in July.
Two sites will open this autumn in Bath city centre and Newcastle’s £25m intu Eldon Square Shopping Centre food quarter.
Smashburger’s first Scottish venue will launch in Glasgow’s Sauchiehall at the end of the year, while a sixth site has been secured at the Junction 9 Retail Park in Wednesbury for an early 2017 opening.
Managing director Tim Lowther – the man behind the launch of Shake Shack and Five Guys in the UK – said: "There's a £2.8bn burger market in the UK and we believe there’s massive room for growth for the right brand. The way we cook our burgers at Smashburger is unique and the result is a much better burger.”
Smashburger plans to open 35 UK sites over the next few years, creating up to 1400 jobs.
The chain was founded in Denver, Colorado in 2007 and now has more than 365 restaurants in seven countries worldwide.
Five Guys - which launched in Virginia, USA in 1986 - beat Nando's to the title of the UK's favourite fast food chain in a Market Force Information Poll this year.