Born in Viiratsi, Kreis Fellin, Governorate of Livonia, Laidoner joined the Imperial Russian Army in 1901 and fought in World War I.

[1] From 1909 to 1912, Laidoner studied at the Imperial Nicholas Military Academy in Saint Petersburg, graduating with a 1st grade diploma.

On 30 October 1911, while studying in Saint Petersburg, Laidoner married Maria Skarbek-Kruszewska, a descendant of Polish nobility, whom he had met earlier in Vilnius.

In October 1915, he was made aide to the commander of the intelligence department of the Staff of the Western Front and on 15 August 1916, Laidoner was promoted to the rank of Podpolkovnik (lieutenant colonel).

[4] On 18 February 1918, the negotiations over the Treaty of Brest-Litovsk broke down and German forces, who had already captured Estonian islands, landed on the mainland.

On 4 April 1918, the Estonian Provisional Government promoted Laidoner, then still residing in Petrograd, to the rank of Polkovnik (colonel).

Laidoner had a crucial role in organizing and training the army in a very short time as well as establishing an effective command structure within the armed forces.

Learning from his experience with trench warfare in World War I and due to the limited size of the forces available to him, Laidoner chose to achieve crucial victories – capturing strategically important roads and railway stations – with smaller and more mobile battalion- and company-sized units, supported by armoured trains and armoured cars.

[3] He served as the chairman of the Foreign Affairs Committee and was part of the Estonian delegation in the General Assembly of the League of Nations from 1922 to 1929, where he was known for his isolationist stance.

[3][7] In 1925, Laidoner was commissioned by the League of Nations to head a special mission to Iraq, investigating the allegations made against Turkey regarding the mistreatment and deportations of Christians in the Mosul region.

[1] On 12 March 1934, the State Elder Konstantin Päts declared martial law and appointed Laidoner commander‑in‑chief of the armed forces.

[7][9] The aim of declaring martial law was to halt the political rise of the Vaps Movement and their potential success in the upcoming presidential elections.

Together with Päts and Kaarel Eenpalu, the Minister of the Interior, Laidoner established an authoritarian rule, disbanding political parties and limiting free speech, the so-called "Era of Silence".

In September 1942, the Laidoners were sent to the Butyrka prison in Moscow, along with Konstantin Päts and a number of former Latvian, Lithuanian and Polish statesmen and their families.

[11] Laidoner's reputation in Estonia has remained controversial;[12] although he has been hailed as a national hero for his leadership skills and success as a military commander in the War of Independence, he has been criticized for his support of Konstantin Päts and his involvement in the 1934 coup d'état as well as the surrender to the Soviet Union in 1940.