She was elected to the French National Assembly on 18 June 2017, representing the 10th constituency of department of Seine-et-Marne, under the investiture of La République En Marche.

[2] Graduate of a Master in Public Management from École nationale d’administration (ENA) and Paris Dauphine University (2014), postgraduate in Global Supply Chain Management at Kedge Business School (2004), Stéphanie Do worked in the first part of her career (2004–2014) in international consulting firms (Capgemini, Sopra Group, Mazars) as a consultant and manager for projects aiming at redressing the economic and social situations of companies in the private and public sectors, associations and local authorities.

As a result, she tabled 63 amendments to the ELAN Bill,[17] 14 of which were adopted.,[18] one of which aimed at providing individualized digital accompaniment, car sharing, bulky removal and recycling in social housing organizations.

Her investment in the ELAN Bill helped her to earn the sixth place in the most influential members of parliament list in 2018 on behalf of "Rumeur Publique" agencies and "Data Observer".

She is the President of a France-Vietnam Friendship Group at the French National Assembly,[24] which allows her to play a role in consolidating the bilateral relationship between France and Vietnam.

In Noisiel, following the relocation of Nestlé France, the largest employer in her constituency, Do interpellated Delphine Gény-Stephann, Secretary of State to the Minister of the Economy, on 22 February 2018 at the hemicycle.

[28] In particular, she supported communes in her constituency to benefit from the Police Security Daily (PSQ) experimentation with the Ministry of the Interior Gérard Collomb in November 2017.

Thus, the municipalities of Champs-sur-Marne, Emerainville and Noisiel had responded positively to the request of the Deputy to support their candidature sending to the Minister of the Interior.

[35] Then, in May 2018, following damage caused by new floods, she again asked Nicolas Hulot for the Seine-et-Marne municipalities benefit from the recognition for natural disaster.

[36] In September 2018, a hundred municipalities of Seine-et-Marne were recognized of natural disaster [34][35], including 4 cities of his constituency (Brou-Sur-Chantereine, Chelles, Lognes and Vaires-sur-Marne).

Since 2017, Do has been working with parents of students from Champs-sur-Marne, Noisiel and Chelles to improve the conditions of school transportation for children on several sections of line 25 in Seine-et-Marne.

[41] On 26 March 2018, Nguyen Phu Trong, General Secretary of the Communist Party of Vietnam was received in the National Assembly as part of his official visit to France.

[42] The next day, the President of the Republic, Emmanuel Macron, invited Stephanie Do to have lunch at the Elysee in honor of the visit of this Secretary General.