Peat began playing basketball at 13. Peat's mother, Marian, encouraged her to join a local basketball team in order to keep her occupied during the schoolsummer holidays. Between 2005 and 2015 Peat played as a point guard for DCU Mercy, helping them win the 2007 and 2011 Basketball Ireland Women's Superleague titles. She also captained DCU Mercy to two National Cup wins in 2010 and 2011 and represented the team at intervarsity level. In addition to playing for DCU Mercy, Peat has also served the club in various other capacities including club captain, coach, administrator and chairperson.
Ireland international
Peat has represented the Ireland women's national basketball team at various age groups from U-16 to senior level. She made her debut for the senior team in 2006 and was co-captain during the 2009–10 season. She has also represented Ireland in EuroBasket Women qualifiers.
Peat played Ladies' Gaelic football at club level for both DCU GAA and Parnells GAA. She was a member the DCU GAA team that won three O'Connor Cup between 2009 and 2011. Peat scored 0–4 as she helped Parnells win the 2015 Dublin Ladies Intermediate Championship.
Inter-county
Peat represented at senior inter-county level and played in three All-Ireland finals, scoring 2–2. In 2009 she scored 0–1 as Dublin lost 1–9 to 0–11 to. In 2010 she scored 0–1 as Dublin defeated by 3–16 to 0–9. In 2014 she scored 2–0 as Dublin lost 2–13 to 2–12 to Cork.
Rugby union
Club and province
Peat was encouraged to play women's rugby union by Graham Byrne, the Dundalk F.C. trainer. He had also worked with Peat as a basketball strength and conditioning coach. Byrne's cousin, Shirley Corcoran, was the director of rugby union at Railway Union and in 2015 Peat eventually accepted a long standing invitation to try out for the Sandymount club. Peat has also represented Leinster in the IRFU Women's Interprovincial Series.
Ireland international
Within months of taking up women's rugby union, Peat was fast-tracked into the Ireland team by Tom Tierney. On 14 November 2015 she made her international debut when she came on as a replacement in an 8–3 defeat against England in an Autumn International at Twickenham Stoop. This was only Peat's eighth ever rugby union match. Peat subsequently represented Ireland at the 2017Women's Rugby World Cup and in the 2016, 2017 and 2018 Women's Six Nations Championships. In 2017 she was voted the Ireland Women's Player of the Year
Personal life
Peat has worked as a clerical officer for the Health Service Executive. She is married to Claire and they have one son, Barra, born in November 2015.