The company has told shareholders it will proceed with the $170 million underground project approximately 110km northwest of Sandfire's Degrussa mine. It is aiming for first production by the first quarter of 2021.
Abra has 34.5 million tonnes of indicated and inferred resources grading 16 grams per tonne silver and 7.2% lead.
The Abra mine will have a 16-year mine life producing a concentrate of about 95,000t of lead and 805,000oz silver annually.
The mine's feasibility study modelled a pre-tax net present value of $553 million an internal rate of return of 39%.
Construction works on site actually began about two years ago with a mine site village built to house as many as 260 workers.
GR Engineering Services was awarded the $75 million key engineering, procurement and construction contract last year.
The contract includes the supply of a 1.2 million tonne per annum lead sulphide floatation process plant and ancillary infrastructure.
Galena managing director Alex Molyneux said he was "ecstatic" to announce a positive FID and the company would soon join "the ranks of high margin Australian producers".
"Everything is now in place and we've been able to make the final investment decision for Abra," he said.
"Galena is now poised … to benefit from buoyant base metals markets."
Molyneux will step down as managing director after seeing the FID through to completion but remain on the Galena board.
Mining engineer Anthony James is to take the wheel.
Last month's commodity outlook from the Minerals Council of Australia predicted silver demand to remain "strong" with prices surging 27% over 2020 levels and only expected to increase as the energy transition got underway.
Silver demand in PV solar industry is expected to triple according to the International Energy Agency.