"We are very pleased to be joining forces with Newstalk as we expand our radio coverage of the Heineken Cup and the Amlin Challenge Cup in Ireland," said ERC Chief Executive Derek McGrath.
"We see Newstalk as an innovative broadcast partner who will add quality and value to both tournaments which continue to go from strength to strength.
"Our continuing relationship with RTE television and radio is also good news for coverage of the Heineken Cup in Ireland."
RTW Radio will now alternate the Irish provinces' live games with Newstalk as part of the new rights arrangement.
The station's Heineken Cup coverage starts on Saturday on RTE Radio 1 with the opening Pool 2 fixture between Leinster and Racing Metro 92 at the RDS.
Later on Saturday evening, RTE Two television will broadcast highlights and analysis of both Munster and Leinster's first round Heineken Cup clashes as well as the best action from Ulster's opening Pool 3 fixture against Aironi Rugby at Ravenhill.
Newstalk's Heineken Cup campaign will kick off on Saturday with live coverage of the eagerly-anticipated Pool 3 clash between London Irish and Munster at the Madejski Stadium.