Ms Cummings, 40, who was a children’s nurse, was found unconscious at a house in Banbridge last weekend. She died a short time later.
The tragedy prompted Women's Aid Armagh Down to organise the vigil at Solitude Park in the Co Down town to remember the 24 other women who have been murdered in Northern Ireland since 2020.
The names of those who lost their lives were poignantly held up by family and friends.
Deputy Lord Mayor of Armagh City, Banbridge and Craigavon Kyle Savage told those gathered that violence against women can "no longer be ignored or tolerated”.
Addressing the crowd, Noel McNally said the murder of Ms Cummings brought back memories of the tragic loss of his daughter Natalie, who was 15 weeks pregnant when she was killed in Lurgan on December 18, 2022.
Eileen Murphy of Women’s Aid Armagh Down thanked everyone who gathered to honour and respect the memory of Karen Cummings and all the other women who have died violently in Northern Ireland.
She urged for more be done by government to tackle violence against women and girls.
1. Candlelit vigil
A large crowd showed their solidarity with the family of murdered nurse Karen Cummings in Banbridge. Photo: Kelvin Boyes / Press Eye
2. Candlelit vigil
The name of Karen Cummings is held up along with those of 24 other women murdered in Northern Ireland since 2020. Photo: Kelvin Boyes / Press Eye
3. Candlelit vigil
Crowds gathered at Solitude Park, Banbridge for Thursday night's vigil. Photo: Arthur Allison/Pacemaker Press
4. Candlelit vigil
Noel McNally, father of Natalie McNally speaks the v𝐢𝐠𝐢𝐥 at Solitude Park in Banbridge on Thursday evening. Also pictured is Deputy Lord Mayor, Councillor Kyle Savage. Photo: Kelvin Boyes / Press Eye