Leslie was recalled by the Senators on Monday, per CBS.
The Senators signed Leslie to a one-year, two-way contract Sunday.
Leslie (shoulder) was injured during practice Thursday and will not participate in the rest of training camp.
Leslie was placed on waivers by the Golden Knights on Friday, Renaud Lavoie of TVA Sports reports.
Leslie signed a one-year, $675,000 contract with Vegas on Thursday.
Leslie inked a one-year, two-way contract with the Kings on Friday.