3rd Brigade may refer to:

Australia

• 3rd Army Tank Brigade (Australia)
• 3rd Brigade (Australia)
• 3rd Light Horse Brigade

Canada

• 3rd Canadian Infantry Brigade

Croatia

• 3rd Guards Brigade (Croatia)

France

• 3rd Mechanised Brigade (France)

India

• British Indian Army in the First World War
  • 3rd (Abbottabad) Brigade
  • 3rd (Ambala) Cavalry Brigade
• British Indian Army in the Second World War
  • 3rd (Meerut) Cavalry Brigade
  • 3rd Indian Infantry Brigade
  • 3rd Indian Motor Brigade

Japan

• IJA 3rd Cavalry Brigade

New Zealand

• 3rd (New Zealand Rifle) Brigade

Poland

• 3rd Brigade of the Polish Legions
• 3rd Polish Infantry Brigade
• Polish 3rd Mountain Brigade

Serbia

• LF 3rd Brigade

South Africa

• 3rd Infantry Brigade (South Africa)

Spain

• 3rd Mixed Brigade

Ukraine

• 3rd Tank Brigade (Ukraine)
• 3rd Separate Assault Brigade (Ukraine)

United Kingdom

• 3rd Cavalry Brigade (United Kingdom)
• 3 Commando Brigade
• 3rd Guards Brigade (United Kingdom)
• 3rd Infantry Brigade (United Kingdom)
• 3rd Mounted Brigade (United Kingdom)
• 3rd Parachute Brigade (United Kingdom)
• Artillery Brigades
  • 3rd Brigade Royal Field Artillery
  • III Brigade, Royal Horse Artillery
  • III Brigade, Royal Horse Artillery (T.F.)

United States

• 3rd Brigade, 1st Infantry Division (United States)
• 3rd Brigade, 1st Cavalry Division (United States)
• 3rd Brigade, 7th Infantry Division (United States)
• 3rd Brigade Combat Team, 10th Mountain Division (United States)
• 3rd Brigade, 24th Infantry Division (United States)
• 3rd Brigade, 104th Division (United States)
• 3rd Marine Expeditionary Brigade (United States)
• 3rd Signal Brigade (United States)
• 3rd Sustainment Brigade (United States)