Associative phase separation within lentil protein isolate (LPI), polysaccharide (κ-carrageenan (κ-CG) and gellan gum (GG)) mixtures was investigated as a function of pH (1.50–8.00) and mixing ratio (1:1–30:1; LPI/polysaccharide) by turbidity and electrophoretic mobility. Effects of salts (NaCl, KCl and CaCl2) on complex stability were also studied as a function of ionic strength. Coacervation typically follows two pH-dependent forming events associated with the formation of soluble and insoluble complexes. The addition of polysaccharides to a LPI system (at all ratios) resulted in a significant drop in turbidity over the entire pH range and a shift in net neutrality to lower pH relative to LPI alone; where LPI aggregation was inhibited by repulsive forces between neighbouring polysaccharide chains. As the biopolymer mixing ratio increased, structure formation was less inhibited. The addition of salts resulted in the disruption of formed LPI/polysaccharide complexes.