Faye Mooney was shot dead along with Nigerian national Matthew Oguche during the attack on the Kajuru Castle villa in Kaduna state on Friday.
Police spokesman Yakubu Sabo said 29-year-old Ms Mooney was among a group of 12 tourists who had travelled from Lagos, and the gunmen kidnapped three other people.
Her family told the Guardian: “Faye was an inspiration to her family, friends, students and work colleagues.
“Her bravery and her belief in a better society took her to places others feared.
“We are so proud of who she was and of everything she achieved in her short life. Her memory will always be cherished.”
Ms Mooney, a graduate of University College London and the London School of Economics, worked as Mercy Corps’ communication specialist in Nigeria and had been at the organisation for nearly two years.
Her career included teaching in Iraq and working in Kosovo to combat human trafficking, according to Mercy Corps.
Ms Mooney’s colleagues were left “utterly heartbroken” at the death of their “dedicated and passionate” workmate, Neal Keny-Guyer, the chief executive of Mercy Corps said.
“Faye was deeply committed to fostering cross-cultural collaboration and was an inspiration to us all,” he said in a statement.
“We extend our deepest sympathy to those who have been affected by this senseless tragedy, including her family, friends and all of our team members in Nigeria who knew her and loved her.
“Our programme operations in Nigeria will continue, but our priority focus at this time remains on the care of the family of our beloved team member and our team in Nigeria.”
The British High Commission in Abuja would not comment on the motive or the nature of the attack.
“We are engaging with the Nigerian authorities, and we understand an investigation is underway,” a statement said.
“The High Commission offers our most profound sympathies and condolences to the family and friends of those impacted in this tragic incident.”
Mr Oguche worked for the International NGO Safety Organisation, a group dedicated to the safety of humanitarian aid workers.
Kaduna state has witnessed a string of kidnappings by armed men in recent months.