Former Swansea coach Laudrup, who had let the Qatari side to two trophy wins, failed to agree terms with the club and is rumoured to be lined up for a return to the Premier League or to take the Denmark national team job.
"The club management saw he was the best to be with the team (for) the next period," a Lekhwiya statement said upon Belmadi's appointment.
Belmadi guided Lekhwiya to their first ever national title in 2011 before leading them to a title defense the following year.
His most recent appointment was with the Qatar national team, but after the 2022 World Cup hosts lost to the UAE, Iran, and Bahrain in consecutive matches, he was replaced by Uruguayan coach Jose Carreno last month.
During his previous spell in charge of the Qatari champions, Belmadi oversaw a AFC Champions League victory over Al Hilal, and he will once again take charge of the side against their countrymen in the quarter-finals of Asia's premier club event.
The first leg takes pace in Riyadh on August 25.