Kersti Kaljulaid took office as Estonia's new President in an inauguration ceremony on Monday.
The new head of stead took the oath of office before Estonia's lawmakers.
Kaljulaid, the first woman to become Estonian president, was elected to the top office last Monday.
The nonpartisan candidate won Estonia's presidential election as a compromise figure after the parliament in August and an electoral college in September failed to elected a president as none of the candidates received the necessary number of votes.
Kaljulaid, 46, graduated from the University of Tartu in 1992 in the field of genetics in the Faculty of Natural Sciences and completed her master's studies in the Faculty of Economics and Business Administration in 2001.
In 1999 she became economic adviser to the then Prime Minister Mart Laar and in 2002 was appointed CFO and CEO of the Iru Power Plant of Estonia's state-owned energy company Eesti Energia. Since 2004 she has been working at the European Court of Auditors.
Kaljulaid is replacing Estonia's outgoing President Toomas Hendrik Ilves whose second term in office ended last Sunday and who under the Estonian constitution was not eligible to stand for a third term.