Maharaj, who made a successful debut for South Africa during the recent Test season, is the only player in the 15-man squad who has not played in a one-day international.
The same squad will represent South Africa in three one-day internationals against England, starting in Leeds on May 24, ahead of the Champions Trophy. South Africa's first match in the ICC event is against Sri Lanka at the Oval on June 3.
Fast bowler Morne Morkel returns to the one-day side after an injury-enforced break and will be part of a strong fast bowling attack which also includes Kagiso Rabada, Wayne Parnell, Chris Morris, Dwaine Pretorius and Andile Phehlukwayo.
Dale Steyn was not considered because he is still recovering from a shoulder injury. But Steyn was included in a South Africa A squad which will play two four-day county matches and a four-day match against England Lions in June.
With South Africa playing an away Test series against England in July and August, the A tour will give Steyn a chance to make a claim to regain his place in the Test squad.
The South Africa A squad will be captained by former South Africa Under 19 captain Aiden Markram, 22, who will be a candidate for an opening batsman berth in the Test series.
The A team includes current or recent Test squad members in Theunis de Bruyn, Temba Bavuma, Dwaine Pretorius, Heinrich Klaasen and Dane Piedt.
Selection convener Linda Zondi said he believed South Africa had picked a squad for all likely conditions during the Champions Trophy.
He said of Maharaj: "Keshav has had an exceptional debut season for the Test side and his inclusion gives us a spinner with different skills and extra batting depth."
The inclusion of orthodox spinner Maharaj meant there was no place for left-arm wrist spinner Tabraiz Shamsi, who was part of a squad which won a one-day series in New Zealand recently.
South African one-day squad: AB de Villiers (capt), Hashim Amla, Farhaan Behardien, Quinton de Kock (wkt), JP Duminy, Faf du Plessis, Imran Tahir, Keshav Maharaj, David Miller, Morne Morkel, Chris Morris, Wayne Parnell, Andile Phehlukwayo, Dwaine Pretorius, Kagiso Rabada.
2017 Champions TrophyAB de VilliersChampions trophychampions trophy 2017Faf du PlessisHashim AmlaImran Tahirkagiso rabadakeshav maharaj
First Published: April 19, 2017, 6:45 PM IST