The campaign will be created by Quiet Storm, which has been appointed to handle the creative account.
The agency will also work on a print and digital campaign.
BetNOW allows any UK-based adult to place bets from their mobile phone or on-line. Customers can place up to £30 of bets from their phone bill or pre-pay account.
It claims to be the “world’s first” instant text betting service.
Betnow was recently replaced by William Hill as partner of The Sun’s fantasy football competition Dream Team.
Quiet Storm won the advertising account following a competitive pitch.
Robert Urwin, chief executive of betNOW, says: “We chose Quiet Storm because they demonstrated a great understanding of our product and presented a great strategy and creative idea”.
Earlier this year, Quiet Storm was appointed to FX UKs advertising roster and created a campaign to push the TV channel’s US show Dexter.