Montigny-l'Allier

{{Use dmy dates|date=August 2023}}

{{Expand French|topic=geo|date=December 2008|Montigny-l'Allier}}

{{Infobox French commune

|name = Montigny-l'Allier

|commune status = Commune

|image = Commanderie de Montigny-l'Allier (02).JPG

|caption = Templar Commandery

|arrondissement = Château-Thierry

|canton = Villers-Cotterêts

|INSEE = 02512

|postal code = 02810

|mayor = Philippe Hennion{{cite web|title=Répertoire national des élus: les maires|url=https://www.data.gouv.fr/en/datasets/r/2876a346-d50c-4911-934e-19ee07b0e503|website=data.gouv.fr, Plateforme ouverte des données publiques françaises|date=9 August 2021|language=fr}}

|term = 2020–2026

|intercommunality = CA Région de Château-Thierry

|coordinates = {{coord|49.1122|3.1039|format=dms|display=inline,title}}

|elevation min m = 55

|elevation max m = 151

|area km2 = 10.14

|population = {{France metadata Wikidata|population_total}}

|population date = {{France metadata Wikidata|population_as_of}}

|population footnotes = {{France metadata Wikidata|population_footnotes}}

}}

Montigny-l'Allier ({{IPA|fr|mɔ̃tiɲi lalje}}) is a commune in the Aisne department in Hauts-de-France in northern France.