The new sales agency, called Virgin Media Solutions, will be led in the UK by Gareth Vaughan Jones, who was previously the head of advertising for Virgin Media UK.
Virgin Media Solutions will represent ad sales for all TV3 Group channels in Ireland and for Virgin Media in the UK, including video on demand and public Wi-Fi services.
The changes mean media agencies will now have a single team to place ads into across the Liberty Global-owned company’s media platforms in the UK and Ireland.
Paula McCarthy, who was previously the brand solutions director at the Irish free-to-air TV network TV3 Group, will lead Virgin Media Solutions Ireland.
Both Vaughan Jones and McCarthy will report to Gavan Byrne, the commercial director for TV3 Group.
Last week Virgin Media and BT released their first joint ad campaign as part of their battle against calls to sell Openreach, BT's network division, which would increase competition in the market for Virgin Media.
David Bouchier, chief digital entertainment officer at Virgin Media, said: "By bringing together the incredibly talented TV3 advertising team with Virgin Media we’re building an advertising arm with firepower across TV, on-demand and Wi-Fi.
"This means agencies now have a single destination to place ads across Virgin Media’s footprint. We’re looking forward to developing our advertising capabilities even further in the near future."