He steps in for Marc Guggenheim, who ran the first season of the Amazon series.
Additionally, series co-creator Travis Beacham, whose 2005 "Black List" script was the basis for the show, has also departed the show over creative differences, reports "hollywoodreporter.com".
Meanwhile, Guggenheim is overseeing "Crisis On Infinite Earths", a crossover involving its Arrow-verse shows and is developing other projects.
Oleson, who signed an overall deal with Amazon Studios in March, will be the third showrunner on "Carnival Row".
The show's co-creator Rene Echevarria initially held the post, and Guggenheim later came aboard. The show's original director, Paul McGuigan, also left and was replaced by Jon Amiel.
Bloom and Delevingne are seen tackling immigration and tribalism issues through the fantasy show. It tells story of a Victorian fantasy world filled with mythological immigrant creatures.
They live in fear of humans, and are forbidden from living, loving and flying with freedom. In this clash between humans and supernatural creatures, a human detective and a faerie become lovers. Amazon renewed "Carnival Row" for a second season a month before its August 30 premiere this year.
Beacham and Guggenheim will keep their credits as executive producers of the series. Oleson, Bloom and Delevingne will also be executive producers on season two, which recently began production in Prague.
( With inputs from IANS )