Pollock was only the fourth fastest Irish athlete but he got the nod ahead of Sergiu Ciobanu, who clocked the third quickest time.
A superb World Half Marathon run sealed Pollock's place along with Belfast's Kevin Seaward and Mick Clohisey.
North Belfast athlete Breege Connolly is in the women's team with Lizzie Lee and Fionnuala McCormack.
Fellow North Belfast competitor Gladys Ganiel is the first reserve for this summer's Games - Barbara Sanchez of Clonliffe Harriers is second reserve.
Ciobanu, who can appeal his exclusion from the team, is first reserve for the men with Rathfarnham's Sean Hehir second reserve.
Pollock, 29, set a personal best of 2:15.38 set in the Berlin Marathon last September but that was bettered by  Ciobanu with 2:15.17.
However, Pollock impressed by finishing 14th at the World Half Marathon in Cardiff in March, with Mo Farah the only European ahead of him.
Pollock hoped to improve his marathon time in London last month but he was forced to pull out because of a foot injury.
Holywood runner Paul Pollock has been selected in the three-man Irish marathon team for the Olympic Games.