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.

Special prosecutors said they raided National Pension Service (NPS) chairman Moon Hyung-pyo's home on Monday, before arresting him on Wednesday.
The NPS is the world's third-largest pension scheme.
It comes amid President Park Geun-hye's impeachment over the scandal involving her longstanding mentor Choi Soon-sil.
In the latest arrest, investigators are looking into NPS's support of an $8bn (£6.5bn) merger between two Samsung Group affiliates and whether Mr Moon used his influence as health minister at the time, to pressure it to back the deal.
The Ministry of Health and Welfare runs the pension service, which manages 545 trillion won ($451bn; £367bn) and was a major shareholder in Cheil Industries Inc and Samsung C&T Corp when they merged.
The NPS has denied previous reports that Mr Moon pressured the organisation to back the deal, and Mr Moon told reporters on Tuesday that he would cooperate with the investigation.
The scandal has also caught Samsung up in allegations that it backed foundations controlled by Choi Soon-sil in the hope of receiving political favours, which investigators are also examining.
Politicians voted on 9 December to impeach President Park - a decision South Korea's constitutional court has six months to uphold or overturn. Until then she remains formally president but stripped of her powers, which are handed to the prime minister, a presidential appointee.
Ms Park denies wrongdoing but has apologised for the way she managed her relationship with Ms Choi, who also denies committing criminal offences.

Mani Kurian, 50, of Eridge Road, Eastbourne, was convicted unanimously by a jury at Lewes Crown Court. He was also found guilty of five sexual assaults and one assault by beating.
A 21-year-old woman was raped as she walked on the upper promenade towards the pier in the East Sussex town at about 02:00 BST on 19 October 2014.
Court officials said Kurian would be sentenced on 26 February.
Holywood runner Paul Pollock has been selected in the three-man Irish marathon team for the Olympic Games.
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South Korea's pension fund head has been arrested in a probe into alleged corruption involving electronic firm Samsung and the country's president.
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A man has been found guilty of raping a woman near Eastbourne Pier.