diff --git a/src/vs/workbench/browser/parts/auxiliarybar/auxiliaryBarPart.ts b/src/vs/workbench/browser/parts/auxiliarybar/auxiliaryBarPart.ts
--- a/src/vs/workbench/browser/parts/auxiliarybar/auxiliaryBarPart.ts
+++ b/src/vs/workbench/browser/parts/auxiliarybar/auxiliaryBarPart.ts
@@ -131,2 +131,5 @@ export class AuxiliaryBarPart extends AbstractPaneCompositePart {
 			}
+			if (e.affectsConfiguration('workbench.secondarySideBar.fontSize')) {
+				this.applyAuxiliaryBarFontSize();
+			}
 		}));
@@ -173,2 +176,4 @@ export class AuxiliaryBarPart extends AbstractPaneCompositePart {
 		container.style.borderRightWidth = borderColor && isPositionLeft ? '1px' : '0px';
+
+		this.applyAuxiliaryBarFontSize(container);
 	}
@@ -234,2 +239,16 @@ export class AuxiliaryBarPart extends AbstractPaneCompositePart {

+	private applyAuxiliaryBarFontSize(container?: HTMLElement): void {
+		const target = container ?? this.getContainer();
+		if (!target) {
+			return;
+		}
+
+		const configuredSize = this.configurationService.getValue<number>('workbench.secondarySideBar.fontSize');
+		if (typeof configuredSize === 'number' && configuredSize > 0) {
+			target.style.setProperty('--vscode-workbench-secondary-sidebar-font-size', `${configuredSize}px`);
+		} else {
+			target.style.removeProperty('--vscode-workbench-secondary-sidebar-font-size');
+		}
+	}
+
 	protected shouldShowCompositeBar(): boolean {
diff --git a/src/vs/workbench/browser/parts/auxiliarybar/media/auxiliaryBarPart.css b/src/vs/workbench/browser/parts/auxiliarybar/media/auxiliaryBarPart.css
--- a/src/vs/workbench/browser/parts/auxiliarybar/media/auxiliaryBarPart.css
+++ b/src/vs/workbench/browser/parts/auxiliarybar/media/auxiliaryBarPart.css
@@ -26,2 +26,6 @@
 }
+
+.monaco-workbench .part.auxiliarybar > .content {
+	font-size: var(--vscode-workbench-secondary-sidebar-font-size, 13px);
+}

diff --git a/src/vs/workbench/browser/parts/sidebar/media/sidebarpart.css b/src/vs/workbench/browser/parts/sidebar/media/sidebarpart.css
--- a/src/vs/workbench/browser/parts/sidebar/media/sidebarpart.css
+++ b/src/vs/workbench/browser/parts/sidebar/media/sidebarpart.css
@@ -20,2 +20,6 @@
 }
+
+.monaco-workbench .part.sidebar > .content {
+	font-size: var(--vscode-workbench-sidebar-font-size, 13px);
+}

diff --git a/src/vs/workbench/browser/parts/sidebar/sidebarPart.ts b/src/vs/workbench/browser/parts/sidebar/sidebarPart.ts
--- a/src/vs/workbench/browser/parts/sidebar/sidebarPart.ts
+++ b/src/vs/workbench/browser/parts/sidebar/sidebarPart.ts
@@ -111,2 +111,5 @@ export class SidebarPart extends AbstractPaneCompositePart {
 			}
+			if (e.affectsConfiguration('workbench.sideBar.fontSize')) {
+				this.applySidebarFontSize();
+			}
 		}));
@@ -150,2 +153,4 @@ export class SidebarPart extends AbstractPaneCompositePart {
 		container.style.outlineColor = this.getColor(SIDE_BAR_DRAG_AND_DROP_BACKGROUND) ?? '';
+
+		this.applySidebarFontSize(container);
 	}
@@ -275,2 +280,16 @@ export class SidebarPart extends AbstractPaneCompositePart {

+	private applySidebarFontSize(container?: HTMLElement): void {
+		const target = container ?? this.getContainer();
+		if (!target) {
+			return;
+		}
+
+		const configuredSize = this.configurationService.getValue<number>('workbench.sideBar.fontSize');
+		if (typeof configuredSize === 'number' && configuredSize > 0) {
+			target.style.setProperty('--vscode-workbench-sidebar-font-size', `${configuredSize}px`);
+		} else {
+			target.style.removeProperty('--vscode-workbench-sidebar-font-size');
+		}
+	}
+
 	private registerActions(): void {
diff --git a/src/vs/workbench/browser/workbench.contribution.ts b/src/vs/workbench/browser/workbench.contribution.ts
--- a/src/vs/workbench/browser/workbench.contribution.ts
+++ b/src/vs/workbench/browser/workbench.contribution.ts
@@ -533,2 +533,18 @@ const registry = Registry.as<IConfigurationRegistry>(ConfigurationExtensions.Con
 			},
+			'workbench.sideBar.fontSize': {
+				'type': 'number',
+				'default': 13,
+				'minimum': 6,
+				'maximum': 32,
+				'markdownDescription': localize('sideBarFontSize', "Controls the font size used for content inside the primary side bar."),
+				'tags': ['accessibility']
+			},
+			'workbench.secondarySideBar.fontSize': {
+				'type': 'number',
+				'default': 13,
+				'minimum': 6,
+				'maximum': 32,
+				'markdownDescription': localize('secondarySideBarFontSize', "Controls the font size used for content inside the secondary side bar."),
+				'tags': ['accessibility']
+			},
 			'workbench.panel.showLabels': {