Ernst is both a surname and a given name, the German, Dutch, and Scandinavian form of Ernest. Notable people with the name include:

• Adolf Ernst (1832–1899) German botanist known by the author abbreviation "Ernst"
• Anton Ernst (born 1975), South African film producer
• Alice Henson Ernst (1880-1980), American writer and historian
• Britta Ernst (born 1961), German politician
• Cornelia Ernst, German politician
• Edzard Ernst, German-British academic
• Emil Ernst, astronomer
• Ernie Ernst (1924/25–2013), American judge
• Eugen Ernst (1864–1954), German politician
• Fabian Ernst, German soccer player
• Gustav Ernst, Austrian writer
• Heinrich Wilhelm Ernst, Moravian violinist and composer
• Jim Ernst, Canadian politician
• Jimmy Ernst, American painter, son of Max Ernst
• Joni Ernst, American politician
• K.S. Ernst, American visual poet
• Karl Friedrich Paul Ernst, German writer (1866–1933)
• Ken Ernst, American comics artist
• Klaus Ernst, German politician
• Konstantin Ernst, Russian media manager, producer and TV host
• Max Ernst, (1891-1976), German artist and painter
• Mensen Ernst (1795–1843), Norwegian road runner and ultramarathonist and one of the first sport professionals
• Morris Ernst, American attorney
• Ole Ernst (1940–2013), Danish actor
• Oswald Herbert Ernst, American general and engineer
• Paul Ernst (American writer), pulp novelist
• Richard R. Ernst (1933–2021), Swiss chemist
• Sipke Ernst (born 1979), Dutch chess grandmaster
• Susan G. Ernst, American developmental biologist
• Tony Ernst, Swedish journalist
• W. G. Ernst, American geologist specializing in petrology and geochemistry
• Walter Ernst, German lawyer and Nazi politician
• Wolfgang Ernst, (1956), German lawyer and legal historian

• Count Ernst of Lippe-Biesterfeld, regent of Lippe
• Ernst Anders, German painter
• Ernest August (disambiguation), multiple people
• Ernst Balz, German sculptor
• Ernst Stavro Blofeld, evil genius from the James Bond novels and films
• Ernst Boepple (1887–1950), German Nazi official and SS officer executed for war crimes
• Ernst Brun Jr., American football player
• Ernst Cassirer, German Jewish philosopher.
• Ernst Chain, German-born British biochemist
• Ernst Cohen, Dutch Jewish chemist known for his work on the allotropy of metals
• Ernst Gebauer, German painter
• Ernst Haeckel, German biologist and illustrator
• Ernst Hammerschmidt (1928–1993), Austrian / German scholar of Ethiopia
• Ernst Happel, Austrian football (soccer) manager
• Ernst Harmse, a Darksouls III enjoyer
• Ernst Reinhold von Hofmann, Russian geologist and mineralogist
• Ernst Jaakson, Estonian diplomat
• Ernst Jansz, Dutch musician and founding member of Doe Maar
• Ernst Jünger (1895-1998), German writer
• Ernst Kaltenbrunner (1903-1946), Austrian-German Nazi SS police chief and war criminal, executed for war crimes
• Ernst Keil (1816–1878), German publisher
• Ernst af Klercker (1881–1955), Swedish general
• Ernst Kummer, German mathematician
• Ernst Laraque, Haitian judoka
• Ernst Larsen, Norwegian athlete
• Ernst Lauda (1859–1932), Austrian engineer
• Ernst Lubitsch (1892–1947), German-born Jewish film director
• Ernst Mach, physicist, coined the term "mach number"
• Ernst Mayr, evolutionary biologist, influential in the philosophy of biology
• Ernst Neizvestny, Russian sculptor
• Ernst Öpik, Estonian astronomer
• Ernst Heinrich Roth, (1877–1948), German luthier
• Ernst Röhm, (1887-1934), German military officer and co-founder of the Nazi SA (Stormtroopers)
• Ernst Rolf, Swedish artist
• Ernst Ruska, a German physicist who won the Nobel Prize in Physics in 1986
• Ernst "Fritz" Sauckel, known as Fritz Sauckel (1894-1946), German Nazi politician, executed for war crimes
• Ernst Scholz (1874–1932), German lawyer and politician
• Ernst Scholz (politician) (1913–1986), German diplomat and politician
• Ernst Sieber (1927–2018), Swiss pastor, social worker, writer, politician and founder of the Sozialwerke Pfarrer Sieber relief organisation
• Ernst Jansen Steur, Dutch notorious former neurologist convicted on over twenty counts of harm
• Ernst Stromer, German palaeontologist
• Ernst Troeltsch, German Protestant theologian
• Ernst Udet, (1896-1941), German flying ace
• Ernst von Hesse-Wartegg, Austrian writer and traveller
• Ernst van de Wetering, Dutch art historian considered to be the world's foremost expert on Rembrandt
• Ernst vom Rath (1909-1938), Nazi German diplomat
• Ernst von der Lancken (1841-1902), Swedish Army major general
• Ernst Zacharias (1924–2020), German musician
• Ernst Zermelo, set theorist
• Ernst Ziegler (1894-1974), German actor
• Ernst Zündel (1939-2017), German neo-Nazi and Holocaust denier

• Ernst, pseudonym used by Matthias Jakob Schleiden

• Herzog Ernst, German medieval epic
• Ernst & Young, professional services and accounting firm
• Ernst Home Centers, a defunct hardware chain
• Ernest (disambiguation)