There has been increasing interest in developing food ingredients for clean-label applications. We have previously shown that heated whey protein and pectin complexes (HCPX) formed at pH above pI have improved emulsification properties and stability when emulsions contained 5% oil. However, it is not fully understood whether these HCPX could stabilize emulsions containing higher oil content as in sauces and salad dressings. The objective of this study was to optimize the emulsification properties of HCPX in emulsions containing 20% oil at pH 5.0. The HCPX were formed by heating mixed 3 wt% whey protein isolate (WPI) and pectin (0, 0.3, 0.45 wt%) at pH 5.5, 5.8, and 6.2 at 85°C for 15 min. Emulsions were made, followed by pH adjustment to 5.0. Final emulsions contained 20 wt% oil, 2 wt% protein and 0 to 0.3 wt% pectin. Emulsification properties were assessed by measuring droplet size, ζ-potential, rheological properties and creaming stability. Emulsions stabilized by heated WPI without pectin had the average droplets sizes >36 μm and ζ-potentials ranging from −27.2 to −19.8 mV. They were not stable and separated into 2 layers within a few hours. The HCPX-stabilized emulsions showed significant improvement in emulsification properties and stability. Mean droplet sizes significantly decreased (P < 0.05) and ranged from 1.6 to 21 μm while droplets became more negatively charged with ζ-potential ranging from −37 to −40.9 mV. Both heating pH and pectin concentration during HCPX formation played important roles on the emulsification properties of the HCPX. The most stable emulsions (>30 d) were those stabilized by HCPX formed with 0.45% pectin at heating pH of 5.5 and 5.8. Formation pH also influenced the rheological behavior of the emulsions with those stabilized by HCPX formed at pH 6.2 being more viscous. These results indicate that emulsification properties of heated WPI and pectin complexes formed at pH > pI can be optimized to stabilize emulsions containing higher oil content. They can be utilized as clean-label ingredients in applications such as sauces and dressings.