Stamford High School, founded in 1877, was an independent school for girls in Stamford, Lincolnshire, England. In 2023, it merged with Stamford School to form a co-educational school.

Stamford High School provided education for students aged 11 (year 7) to 18 (year 13). From 2000 until 2023, Sixth form teaching was carried out jointly with Stamford School. The school belonged to the Stamford Endowed Schools, a member of the Headmasters' and Headmistresses' Conference.

The school was founded in 1877 and, until it merged in 2023, stood on its original site on High Street, St Martin's, the part of Stamford south of the River Welland. The partner school, Stamford School was founded in 1532.

The funds for the foundation of the High School and the further endowment of the existing boys' school were appropriated from the endowment of Browne's Hospital by Act of Parliament in 1871. This trust had originally been established for the relief of poverty by William Browne (died 1489), a wealthy wool merchant and alderman of the town.

In recent years, the two schools were united under the leadership of a single principal as the Stamford Endowed Schools. This organisation comprised Stamford Junior School, a co-educational establishment for pupils aged between 2 and 11 years and Stamford School and Stamford High School for students aged 11–18. Sixth form teaching was carried out jointly between Stamford School and Stamford High School.

Stamford Endowed Schools became co-educational from September 2023 and fully co-educational in every year group from 2024. The High School site is now used as a bespoke Sixth Form campus, named 'St Martin's'.

There was a house system for all students with houses named after famous heroines - Cavell, Beale, Anderson and Eliot. In the merger with Stamford School, the houses from both schools have joined together. Beale and Anderson are houses for Years 7-9 and Eliot and Cavell for Years 10-13.

This article's list of alumni may not follow Wikipedia's verifiability policy. Please improve this article by removing names that do not have independent reliable sources showing they merit inclusion in this article AND are alumni, or by incorporating the relevant publications into the body of the article through appropriate citations. (June 2012)

• Izzy Bizu, singer-songwriter
• Sarah Cawood
• Paule Constable, stage lighting designer
• Rae Earl
• Anita Ganeri, children's author
• Daphne Ledward, Gardeners' Question Time panellist
• Claire Lomas
• Sarah Outen, first woman to row solo across the Indian Ocean

• Official website
• Profile on MyDaughter
• Profile on the ISC website
• ISI Inspection Reports