Under the agreement, Endeavour will offer 0.0187 of an Endeavour share in exchange for each Avnel share.
Avnel holds an 80% interest in the Kalana project and also exploration permits in the surrounding area.
With an 18-year mine life, the fully permitted feasibility-stage project is based on a 1.2Mtpa carbon-in-leach plant and a single open-pit constrained reserve of around 2.0Moz grading 2.8g/t.
A feasibility report indicated that Kalana has an expected production of 101,000oz per annum, with an after-tax net present value at a 5% discount rate of $257m, and an after-tax internal rate of return (IRR) of 38%.
Endeavour Mining president and CEO Sébastien de Montessus said: "We believe that Kalana fits well within our strategy of building a high-quality portfolio of long-life, low all-in sustaining cost (AISC) assets with exploration upside.
"Furthermore, this acquisition expands our footprint in Mali and reinforces our project pipeline, which will allow us to continue to leverage our in-house construction expertise."
Endeavour plans to re-design the current feasibility study and expand the plant capacity.
In addition, the company intends to commence a new exploration programme to tap additional potential.
The transaction is subject to customary conditions, including shareholder approval receipt of sanction by the Guernsey Royal Court and is scheduled to close in September this year.