Castelletto d'Orba

{{Infobox Italian comune

| name = Castelletto d'Orba

| official_name = Comune di Castelletto d'Orba

| native_name =

| image_skyline = Castelletto d'Orba-castello1.jpg

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| image_shield = Castelletto_d_Orba-Coat_of_Arms.png

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| coordinates = {{coord|44|41|N|8|42|E|type:city(1,979)_region:IT|display=inline,title}}

| coordinates_footnotes =

| region = Piedmont

| province = Alessandria (AL)

| frazioni = Cazzuli, Crebini, Passaronda

| mayor_party =

| mayor = Mario Pesce

| area_footnotes =

| area_total_km2 = 13.98

| population_footnotes = All demographics and other statistics: Italian statistical institute Istat.

| population_total = 1958

| population_as_of = 31 May 2018

| pop_density_footnotes =

| population_demonym = Castellettesi

| elevation_footnotes =

| elevation_m = 200

| twin1 =

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| postal_code = 15060

| area_code = 0143

| website = {{official website|http://www.comune.castellettodorba.al.it/}}

| footnotes =

}}

Castelletto d'Orba is a comune (municipality) in the Province of Alessandria in the Italian region Piedmont, located about {{convert|90|km|mi}} southeast of Turin and about {{convert|25|km|mi}} south of Alessandria.

Castelletto d'Orba borders the following municipalities: Capriata d'Orba, Lerma, Montaldeo, San Cristoforo, and Silvano d'Orba.