Nitrobenzene (NB) is considered a toxic and potential carcinogen. Continuous contamination has resulted in an urgent need for remediation. Fenton reagent provides an advanced oxidation process that is capable of remediating recalcitrant nitroaromatic compounds, such as NB. However, one drawback of Fenton chemistry is that the reaction requires acidic pH to prevent precipitation of iron. Our studies have investigated Fenton conversion of NB at near-neutral pH with several organic additives: β-cyclodextrin (β-CD), hydroxypropyl-β-cyclodextrin (HPCD), carboxymethyl-β-cyclodextrin (CMCD), and polyethylene glycol (molecular weight (MW) = 200, 400, and 600) for developing a process for treating NB-contaminated waters. The main factors influencing NB conversion, such as iron concentration, hydroxyl radicals (·OH) scavengers, and kinds or concentration of organic additives, were examined. Meanwhile, the reactive mechanisms and kinetics were investigated for Fenton conversion of NB. The results show that organic additives for Fenton process should be a good alternative for the advanced treatment of NB at near-neutral pH.