Mia Costello

Mia C. Costello (born January 11, 1968)^[1] is a Republican politician from Alaska. She is a member of the Alaska House of Representatives from the 15th district. She previously represented the 20th district from 2011 to 2015 and served as a member of the Alaska Senate, representing District K from 2015 to 2023.

Preceded byPeter Micciche

Succeeded byLyman Hoffman

Preceded byLesil McGuire

Succeeded byBill Wielechowski

Quick facts Majority Leader of the Alaska Senate, Preceded by ...

Mia Costello
Majority Leader of the Alaska Senate
In office January 15, 2019 – July 8, 2019
Preceded by	Peter Micciche
Succeeded by	Lyman Hoffman
Member of the Alaska Senate from the K district
In office January 20, 2015 – January 17, 2023
Preceded by	Lesil McGuire
Succeeded by	Bill Wielechowski
Minority Leader of the Alaska House of Representatives
In office January 21, 2025 – November 22, 2025
Preceded by	Calvin Schrage
Succeeded by	DeLena Johnson
Member of the Alaska House of Representatives
Incumbent
Assumed office January 21, 2025
Preceded by	Tom McKay
Constituency	15th district
In office January 18, 2011 – January 20, 2015
Preceded by	Bob Buch
Succeeded by	Mike Hawker
Constituency	27th district
Personal details
Born	(1968-01-11) January 11, 1968 (age 58) Anchorage, Alaska, U.S.
Party	Republican
Spouse	Andrew Billings
Education	Harvard University (BA) University of Alaska, Southeast (MA)
Website	Campaign website

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In November 2010, Costello defeated Democratic incumbent Bob Buch to win her House seat. Costello received 3,696 votes to Buch's 2,873.^[2] Costello served on the House Finance Committee and as chair of the Natural Resources Finance Subcommittee. She ran for the Senate seat vacated by Democrat Hollis French in 2014, picking up the seat to add to the Republican Senate Majority.^[3]

Costello served as minority leader for the 2025 legislative session but resigned the position in November 2025.^[4]

Prior to being elected to the Alaska State House, Costello worked as a school teacher, legislative aide, and as deputy communications director for Governor Frank Murkowski.^[5]

After graduating from West High School, she earned her B.A. from Harvard University and later a Master of Art in Teaching from the University of Alaska Southeast.^[6]