Steve Tyler, of the Gin Tub, blames social media for "killing pubs".
He has built an electronic shield, known as a Faraday cage, into the walls and ceiling to stop the signals penetrating the building.
But one social media expert suggested the move would not attract younger drinkers to the East Sussex bar.
Mr Tyler said he wanted to force "people to interact in the real world" and remember how to socialise.
"If the person you are with goes to the bathroom, the problem with mobiles is they insulate you from talking to other people," he said.
"I want you to enjoy the experience of going out."
The tables at the bar, in Hove, East Sussex, feature old-style phones for drinkers to call for another round or chat to people on other tables.
But, social media expert Zoe Cairns said: "Mobile phones are every part of our life now and if we go into a bar, a club and we are looking for our phones, it does take away that socialising aspect of it.
"But I do believe [the idea] is going to isolate that particular generation."
The Faraday cage, a metal construction which traps electromagnetic waves, is named after 19th Century British scientist Michael Faraday.
Not only does it affect mobile signals, any device containing a radio-frequency identification (RFID) chip, such as a passport, travel card or credit card, is unable to receive or transmit data.
Mr Tyler claimed use of the cage was permitted under the 2006 Wireless Telegraphy Act, unlike phone mobile jammers, which transmit their own signal to prevent a handset accessing its base station.
A new cocktail bar has blocked mobile phone signals to try to encourage its customers to stop looking at their screens and talk to each other instead.