Joining him at 10-under par is Victorian amateur Marc Leishman, who trailed by three going into the third round. However, a 6-under-par 65 vaulted Leishman into a tie as Bonhomme posted a 3-under 68.
The duo are fours shots clear of New South Wales Andre Stolz, who also fired a 65 to move to 6-under.
Adrian Percey, who held the lead the first two days, exploded with a 7-over 77 and dropped to 1-under for the tournament.
New South Wales David Bransdon carded a course-equaling record 7-under 63 to join Western Australias Steve Collins (66) at 5-under.
Three other golfers stand six off the pace.