Saavedra Lamas was a distinguished student at Lacordaire College and at the University of Buenos Aires where he received the Doctor of Laws degree in 1903, summa cum laude. After study in Paris and travel abroad, he accepted a professorship in law and constitutional history at the University of La Plata, where he began the teaching career that was to span more than forty years. Later, he inaugurated a course in sociology at the University of Buenos Aires, taught political economy and constitutional law in the Law School of the university, and eventually served as the President of the university.

Saavedra Lamas began his political career in 1906 as Director of Public Credit and then became the secretary-general for the municipality of Buenos Aires in 1907. In 1908 he was elected to the first of two successive terms in Parliament. There he initiated legislation regarding coastal water rights, irrigation, sugar production, government finances, colonization, and immigration. His main interest, however, lay in foreign affairs. He provided leadership in saving Argentina's arbitration treaty with Italy, which almost foundered in 1907-1908, and eventually became the unofficial adviser to both the legislature and the foreign office on the analysis and implications of proposed foreign treaties.

Appointed minister of Justice and Education in 1915, he instituted educational reforms by integrating the different divisions of public education and by developing a curriculum at the intermediate level for the vocational and technical training of manpower needed in a developing industrial country.

Saavedra Lamas was a leading Argentine academician in two areas. A pioneer in the field of labor legislation, he edited several treatises on labor legislation in Argentina and on the need for a universally recognized doctrine on the treatment of labor - among them, Centro de legislacíon social y del trabajo (1927) [Center of Social and Labor Legislation], Traités internationaux de type social (1924), Código nacional del trabajo (three volumes, 1933) [National Code of Labor Law]. In the arena of practical affairs, Saavedra Lamas drafted legislation affecting labor in Argentina, supported the founding of the International Labor Organization in 1919, and presided over the ILO Conference of 1928 in Geneva while serving simultaneously as leader of the Argentine delegation.

In international law, his other field of major scholarly interest, he published "La Crise de la codification et de la doctrine Argentine de droit international" (1931); and he spoke, wrote, or drafted legislation on many subjects with international ramifications - among them, asylum, colonization, immigration, arbitration, and international peace. His brief Vida internacional, which he wrote at the age of seventy, is an urbane by-product of all this study and experience.

His work in ending the Chaco War between Paraguay and Bolivia (1932–1935) had not only local significance but generalized international importance as well. When he took over the foreign office, he immediately engaged in a series of moves to lay the diplomatic groundwork for a negotiated settlement of this dispute. In 1932 he initiated at Washington the Declaration of August 3 which put the American states on record as refusing to recognize any territorial change in the hemisphere brought about by force. Next, he drew up a Treaty of Nonaggression and Conciliation which was signed by six South American countries in October, 1933, and by all of the American countries at the Seventh Pan-American Conference at Montevideo two months later. In 1935 he organized mediation by six neutral American nations which resulted in the cessation of hostilities between Paraguay and Bolivia. Meanwhile, in 1934, Saavedra Lamas presented the South American Antiwar Pact to the League of Nations where it was well received and signed by eleven countries. Acclaimed for all of these efforts, he was elected President of the Assembly of the League of Nations in 1936.

After his retirement from the foreign ministry in 1938, Saavedra Lamas returned to academic life, became President of the University of Buenos Aires for two years (1941–1943), and rounded out his career as a professor for an additional three years (1943–1946).

He died in 1959 at the age of eighty from the effects of a brain hemorrhage.

In August 2014 a project for rebuying his Nobel medal by the Argentine Nation was presented at the Argentine congress.