diff --git a/.changeset/dull-toys-crash.md b/.changeset/dull-toys-crash.md
new file mode 100644
index 00000000000..29698b8b3d0
--- /dev/null
+++ b/.changeset/dull-toys-crash.md
@@ -0,0 +1,5 @@
+---
+'@primer/components': minor
+---
+
+Default portal containers created by primer are absolutely positioned at 0,0
diff --git a/src/Portal/Portal.tsx b/src/Portal/Portal.tsx
index e8348ef776b..a2eaf32fecc 100644
--- a/src/Portal/Portal.tsx
+++ b/src/Portal/Portal.tsx
@@ -26,6 +26,9 @@ function ensureDefaultPortal() {
     if (!(defaultPortalContainer instanceof Element)) {
       defaultPortalContainer = document.createElement('div')
       defaultPortalContainer.setAttribute('id', PRIMER_PORTAL_ROOT_ID)
+      defaultPortalContainer.style.position = 'absolute'
+      defaultPortalContainer.style.top = '0'
+      defaultPortalContainer.style.left = '0'
       const suitablePortalRoot = document.querySelector('[data-portal-root]')
       if (suitablePortalRoot) {
         suitablePortalRoot.appendChild(defaultPortalContainer)
diff --git a/src/__tests__/__snapshots__/AnchoredOverlay.tsx.snap b/src/__tests__/__snapshots__/AnchoredOverlay.tsx.snap
index c98f4d4583d..0773df5c1ac 100644
--- a/src/__tests__/__snapshots__/AnchoredOverlay.tsx.snap
+++ b/src/__tests__/__snapshots__/AnchoredOverlay.tsx.snap
@@ -206,6 +206,7 @@ Object {
         </button>
         <div
           id="__primerPortalRoot__"
+          style="position: absolute; top: 0px; left: 0px;"
         >
           <div
             style="position: relative; z-index: 1;"
@@ -250,6 +251,7 @@ Object {
       </button>
       <div
         id="__primerPortalRoot__"
+        style="position: absolute; top: 0px; left: 0px;"
       >
         <div
           style="position: relative; z-index: 1;"