The bio-oil produced by the catalytic pyrolysis of waste cooking oil (WCO) has great potential to become a substitute for fossil fuels. However, the low yield and high oxygen content of pyrolysis oil result in low added value. The low-cost production of high-yield and high-quality hydrocarbon-rich pyrolysis oil remains challenging. To efficiently convert WCO to high quality hydrocarbon-rich pyrolysis oil, a nickel oxide loaded activated carbon catalyst (Ni/AC) was introduced in the ex-situ catalytic system. The catalytic pyrolysis results showed that the catalyst exhibited high deoxygenation activity and the hydrocarbon content in the bio-oil could reach up to 99%. The selectivity of total aromatic hydrocarbons and monocyclic aromatic hydrocarbons in liquid oil could reach 86.38% and 68.47%, respectively. By extracting hydrogen from hydrocarbon fragment, the NiO site facilitates dehydrogenation, resulting in a gaseous product with syngas (CO, H₂) as the main component, with a maximum syngas concentration of 70%. The hydrogen produced is favorable for hydrogen transfer reactions and as a result promotes deoxygenation and hydrocarbon production. This study provides valuable insight into a low-cost, efficient, and high-value-added way to recover WCO. It will avoid the risk of environmental pollution caused by WCO and provide a reference for the sustainable use of waste.