Kourtney Kardashian took to her Instagram stories to share her tribute with her 74.8million followers.
The mum-of-three said she has been “physically sick” since hearing of the attack, which took place in the Christchurch mosque.
At the time of the attack, Muslims were busy worshipping before the white supremacist entered their place of worship and opened fire.
“I have been physically sick all day after hearing about the senseless, hateful acts in New Zealand this morning”
Up to 41 people died at one mosque, seven at another and one person died in hospital.
Kourtney wrote: “I have been physically sick all day after hearing about the senseless, hateful acts in New Zealand this morning.
“As a Christian, I believe hate is wrong in any form…
“We need to walk in love…
“For all people and all religions, I stand with my Muslim brothers and sisters.”
The white Australian right-wing terrorist – named in local media as Brenton Tarrant – livestreamed his sickening shooting spree on Facebook.
The shooter, who identified himself on Twitter as “Brenton Tarrant” from Grafton, New South Wales, stormed into Masjid Noor Mosque in Christchurch around 1.40pm local time, gunning down dozens while hundreds of worshipers took part in Friday prayer.
Ten people were later killed at the Linwood Islamic Centre, four miles (6km) away.
In the aftermath of the bloody attacks, three men and one woman were arrested, with police charging “one man in his late 20s” with murder.