Poem launches with a brief to provide measurable results in the direct media field.
It will launch with billings in excess of £80 million as the three managing partners will combine their current businesses to form the company.
Prager's pimedia agency, whose clients include Slendertone and Greenpeace, will merge with Orca Media, a list and data-broking service owned by Andrew Creed and Ekay, a financial media specialist owned by Eddie Powell.
Poem will have a staff of around 30 and will focus on growing new business from financial, mail order, charities and the not-for-profit sector.
Poem will combine media planning and buying skills with specialist data and consumer insight supplied by Orca.
Creed founded Orca with his business partner Martin Douglas and has worked with agencies including Wunderman on its Ford and Jaguar business and Proximity on RNLI.
Prager, a founder of CIA Direct in 1986, left Prager Proximity in 2002 to launch pimedia. Powell worked in ad sales at Mirror Group Newspapers before launching Ekay in 1994.
"With direct media, integration of services is really important but we need to put in-depth skills together," Prager said. "Data is such a complex area and with list-buying skills as well this can put you at the top table."