Sarah Brown paid tribute to her friend and colleague Jo Cox describing her as a "lively" and "bright" person.
Ms Cox worked with Mrs Brown at Number 10 after leaving Oxfam to join her maternal mortality campaign.
As director of that campaign, Ms Cox was "really committed to helping the most marginalised, poorest families and children around the world," Mrs Brown said.
Fundraising page set up by the MP's family hits the landmark total as thousands donate to good causes in her memory.
The MP had also recorded a video about Islamophobia in Yorkshire - described as a 'hotbed of far-right activity', according to The Times.
Emotional tributes have been paid to Jo Cox tonight as vigils were held around the UK in honour of the murdered MP.