Sears finished with 16 points, eight rebounds, seven assist and eight blocked shots - the last two of which were career highs. Makai Mason scored 12, Brandon Sherrod added 10 with seven rebounds and guard Nick Victor had nine points and a career-high tying 11 rebounds.
Yale (3-0) opened the season with three straight victories for the first time since the 1950-51 season.
Yale answered with an 11-0 run over the next two-plus minutes, during which Mason made 7 of 8 free throws, to seal it.
Austin Price led Lehigh (0-3) with 23 points.