The newly-reformed pop group will follow April's nationwide tour with a summer concert at the venue on July 22 as part of Forestry Commission Live Music.
Singer Ian Watkins said: "We are all really up for performing our hits in such a fantastic setting and promise a Steptacular show."
Tickets go on sale this Friday, January 27 at 9am and are priced at £36. Tickets are available from the Forestry Commission Live Music website.
Steps topped the UK album chart last October with their comeback greatest hits compilation The Ultimate Collection.
Other artists confirmed for various Forestry Commission shows this year include Madness, Will Young, Ed Sheeran, The Wombats, Plan B and The Darkness.
> Steps: 'The Ultimate Collection' - Album review
Watch Steps talk about their comeback to Digital Spy below: