On 11 March 2012, 23-year old Merah shot dead French paratrooper Imad Ibn Zaiten after Merah arranged to meet Zaiten and buy his motorcycle.
Merah then killed two other soldiers four days later in nearby Montauban before killing a Rabbi and three girls at a Jewish school on 19 March.
Merah was himself killed three days later after a dramatic siege in his apartment in Toulouse.
A year on, the French Defence Minister, Jean-Yves Le Drian, awarded Imad Ibn Zaiten the Legion d’Honneur posthumously at a ceremony at the air base in Toulouse where he was based.
Zaiten’s mother, Latifa Ibn Zaiten says it is still hard for her to come to terms with her son’s death.
“Today is a great honour for my son and his memory…[but] today is the day my son was killed; it’s a very difficult day,” she told journalists while holding back tears.
She later helped to unveil a plaque at the site where her son was killed.
“The name of your son resonates painfully a year after the first of the horrible killings perpetrated by this criminal. We will never forget this name,” the mayor of Toulouse, Pierre Cohen, says.
Local Imams also held a prayer service.
Toulouse has begun a week of commemorations to remember the tragedy. On Sunday, French President François Hollande is due to take part in a march to remember Merah’s seven victims.