The three-time premiership winner and three-time All-Australia will be officially unveiled as coach at a media conference in Melbourne on Wednesday.
The Lions announced the appointment on their website on Tuesday night after a day of speculation Leppitsch would take over from the sacked Michael Voss.
"The Brisbane Lions are pleased to announce the appointment of Justin Leppitsch as Senior Coach," a statement on the website read.
But the Lions' messy board wrangle continues to drag on, and may yet remain unresolved after the appointment of Leppitsch as sacked Michael Voss' successor.
A faction including former coach Leigh Matthews is aiming to oust current Lions chairman Angus Johnson after Johnson's role in Voss' sacking, and a bungled approach to replace him with Paul Roos in August.
Matthews and Johnson both attended mediation talks along with other Lions board members and AFL heavyweights in Melbourne on Tuesday.
In a short statement, the Lions said the meeting between the club's divided board and the AFL had been "constructive" although no resolution was reached.
They say further discussions will be held later this week.
If those fail to convince Johnson to bow out gracefully - as appears the most likely outcome - an extraordinary general meeting will be the next step.
But the board did manage to find some common ground on Tuesday, with a hastily convened meeting in Melbourne ratifying Richmond assistant Leppitsch's ascent to the Lions' head coach role.
Leppitsch, who played 227 games for the Lions, has been an assistant coach at Richmond for the past four years.
Leppitsch has previously been an assistant at the Lions - under both Matthews and briefly Voss.
With financial problems hanging over the club, the continuing board uncertainty and the void since Voss' late-season departure, the Lions' young players are rushing for the exit door.
Already a swag of top 30 draft picks have made it clear they want out, among them Billy Longer, Elliot Yeo and Jared Polec.
Half-forward Patrick Karnezis is all but gone - most likely to Collingwood, while defender Sam Docherty has reportedly spoken to several clubs in Melbourne.
Carlton have already offered a deal to veteran Brent Staker.
And veteran duo Jonathan Brown and Simon Black's futures remain up in the air - Brown's situation complicated by a serious late-season foot injury and two recent bouts of surgery.