Methods and systems for producing jet-range hydrocarbons are disclosed herein. In an exemplary embodiment, a method for producing jet-range hydrocarbons includes the steps of combining a first stream including C4 olefinic hydrocarbons and a second stream including C5-C8 olefinic hydrocarbons to produce a third stream including C4-C8 hydrocarbons, oligomerizing the third stream including C4-C8 olefinic hydrocarbons to produce a fourth stream including C4-C20 olefinic hydrocarbons, and separating C5-C8 hydrocarbons from the fourth stream including C4-C20 olefinic hydrocarbons to produce the second stream including C5-C8 olefinic hydrocarbons and a fifth stream including C9-C20 olefinic hydrocarbons. The method further includes the step of hydrogenating the fifth stream including C9-C20 olefinic hydrocarbons to produce a sixth stream including C9-C20 paraffinic jet-range hydrocarbons.