Not properly a Harvey company, this was one of two companies owned by Leo Greenwald who also worked for distributor P.D.C. The other company was Speed Publishing Company, which published two issues of Speed Comics. Both of these companies sold (or by some accounts gave) their titles to early Harvey companies (in this case Family Comics, Inc.) whose titles were also being distributed by P.D.C.
Champ Publishing Company bought (and/or was created to publish) Champion Comics, previously published by Worth Publishing Company, Inc. It was renamed to Champ Comics, with the first issue under the new name (#11) still published by Worth Publishing Company, Inc. but already edited and (according to the statement of ownership in issue #12) co-owned by Leo Greenwald.
Address for both Champ Publishing Company and Leo Greenwald (indicia for Champ Comics #12 as well as October 1st, 1941 Statement of Ownership from #17): 225 West 56th Street, New York, N. Y.
Address for both Worth Publishing Co., Inc. and Leo Greenwald (October 14th, 1940 Statement of Ownership from #12) 122 East 42nd St., New York, N. Y.
See also Bilbara Publishing Co., Inc. and Hit Publishing Co. Inc., as both along with Worth Publishing Co., Inc. were related to Worth Carnahan.