Events from the year 1721 in Sweden

• Monarch – Frederick I

• 15 April - A great fire in Gothenburg.
• 25 May - The Battle of Sundsvall during the Russian Pillage of 1719-1721.
• May to June - Hudiksvall, Härnösand, Piteå, Sundsvall, Söderhamn and Umeå are burned by the Russians during the Russian Pillage of 1719-1721, but Gävle is successfully defended.
• - September 10 – The Treaty of Nystad is signed, ending the Great Northern War.
• Den Gyldene Freden
• The first theater performance is presented at the Bollhuset for fifteen years, since the theater is opened again after the war.
• The Maria Ersdotter case.

• Catharina Elisabet Grubb, industrialist (died 1788)
• Fredrik Henrik af Chapman, shipbuilder, scientist and officer (died 1808)

• Maria Ersdotter, criminal (born 1685)