Lukaszuk becomes the third candidate in the contest to replace former premier Alison Redford.
He says he has collected the required 500 signatures from party members and paid the $50,000 non-refundable deposit.
Calgary legislature member Ric McIver and former Calgary MP Jim Prentice earlier filed their papers and paid the fee.
Nominations closed Friday afternoon and no one else has publicly declared themselves a candidate.
Party members are to vote for their new leader in September. (CHED)