Karrieren blev indledt i Justitsministeriet, hvor Gitte blandt andet arbejdede for anklagemyndigheden og som dommerfuldmægtig. Hun har en LL.M. fra University of Cambridge, og i 2000 opnåede hun kvalifikation som engelsk solicitor fra BPP Law School i London, samtidig med at hun arbejdede for Charles Russell Solicitors, London, i firmaets afdeling for selskabs- og konkurrenceret.
Gitte har været involveret i en lang række fremtrædende konkurrenceretssager i Danmark og EU, bl.a. vedrørende den danske stats salg af aktier i DONG Energy til Goldman Sachs, ATP og PFA og EY's overtagelse af KPMG's danske aktiviteter. Hun har særlig stor ekspertise inden for M&A-relateret konkurrenceret, herunder i forbindelse med anmeldelser af europæiske og multi-nationale fusioner.
Udbudsret er et andet af Gittes specialer, både på EU-niveau og i Danmark. Hun bistår ordregivende myndigheder, som f.eks. Sund & Bælt Holding i relation til opførelsen af den faste forbindelse over Femern Bælt. Hun bistår også leverandører, herunder særligt leverandører indenfor lægemiddelindustrien, hvor hun har opnået positive resultater i adskillige sager for Klagenævnet for Udbud.
Gitte har været udnævnt til sagkyndigt medlem af Klagenævnet for Udbud og er medlem af Danske Advokaters ekspertpanel for udbudsret.
Gitte Holtsø is ranked as a leading individual as regards Competition/European Law as well as Public Procurement by Chambers Europe. Department head Gitte Holtsø is active in both competition and public procurement cases. She often represents clients before the competition authorities. Interview-ees emphasise her trustworthy advice, saying: "She is highly skilled and knows our business very well. You feel safe when she is advising." (2019)
Gitte Holtsø is ranked as a leading individual as regards Competition/European Law as well as Public Procurement. "Head of department Gitte Holtsø is lauded by clients as "very practical, highly skilled" and "always available". She practises in all areas of competition law and public procurement, including high-profile merger control and antitrust matters. Clients are impressed by her informed and tailored approach, with one source reporting: "She is energetic and interested in clients and how their businesses operate". (2018)
Gitte Holtsø is recommended as regards EU and Competition. "Exceptionally specialized" Gitte Holtsø leads the group. (2018)
Gitte Holtsø is listed as an expert with respect to both Competition and Government Contracts. (2017)
Gitte Holtsø is ranked as a leading individual as regards Competition/European Law. Gitte Holtsø handles handles a range of matters within the sector, including high-profile antitrust cases, public procurement and competition-related M&A matters. Clients say: "She is really good, very skilled and knowledgeable. Having worked with her for a while, you can tell that she really knows what she's doing". (2017)
Gitte Holtsø is ranked as a leading individual as regards Public Procurement. (2017)
Gitte Holtsø is recommended as regards EU and Competition. Highly recommended group head Gitte Holtsø. (2017)
Gitte Holtsø is recommended as regards EU and Competition. Gitte Holtsø is highly regarded for her "stellar, solution-oriented approach". (2016)
Gitte is listed as the only individual within Competition and Antitrust - Denmark (Women in Business Law). (2014, 2015, 2016)
Gitte Holtsø is listed as an expert with respect to Government Contracts.
Gitte Holtsø is listed as an expert with respect to Competition. (2016)