High-order Laguerre–Gaussian (LG) petal-like beams have become a topic of significant interest due to their potential application in next-generation optical trapping, quantum optics, and materials processing technologies. In this work, we demonstrate the generation of high-order LG beams with petal-like spatial profiles and tunable orbital angular momentum (OAM) in the mid-infrared wavelength region. These beams are generated using idler-resonant optical parametric oscillation (OPO) in a KTiOAsO4 (KTA) crystal. By adjusting the length of the resonant cavity, the OAM of the mid-infrared idler field can be tuned and we demonstrate tuning in the range of 0 to ±10. When using a maximum pump energy of 20.2 mJ, the maximum output energy of high-order modes LG0,±5, LG0,±8, and LG0,±10 were 0.8, 0.53, and 0.46 mJ, respectively. The means by which high-order LG modes with petal-like spatial profiles and tunable OAM were generated from the OPO is theoretically modeled by examining the spatial overlap efficiency of the beam waists of the pump and resonant idler fields within the center of the KTA crystal. The methodology presented in this work offers a simple and flexible method to wavelength-convert laser emission and generate high-order LG modes.