She was born in Trondheim as a daughter of Ralph Tambs-Lyche and Elsa Rasmussen. Her father was a mathematician and Mot Dag affiliate, and from an early age Guri Tambs-Lyche was influenced by her father"s speeches in the Student Society in Trondheim. Her mother was a pioneer in maternal hygiene work.
She studied technical drawing at the Norwegian National Academy of Craft and Art Industry, and joined the Workers" Youth League while studying.
Her father eventually became a professor Her job was to distribute illegal newspapers. After the war she joined the Communist Party of Norway, and wrote in Friheten, but she was excluded in the aftermath of the Peder Furubotn case.
In 1954 the organization became a part of Norsk Kvinneforbund.
She was on the editorial board of their magazine Kvinner hjemme og ute, later named Kvinner i tiden, and was editor-in-chief for a time. She also participated on international women"s congresses.
After the disbanding of Norsk Kvinneforbund, she became a prominent member in the national branch of the Women"s International League for Peace and Freedom. She lived in Lund, Sweden for the last two years of her life, and died her home on March 2008.
