diff --git a/.github/workflows/nightly-verify.yml b/.github/workflows/nightly-verify.yml
index b565b06c40..c1eca77e0f 100644
--- a/.github/workflows/nightly-verify.yml
+++ b/.github/workflows/nightly-verify.yml
@@ -180,6 +180,9 @@ jobs:
       - name: Verify
         if: matrix.os != 'windows-latest'
         env:
+          # /tmp is too small on Ubuntu 26.04-based runners
+          # (https://github.com/actions/runner-images/issues/14777)
+          ARROW_TMPDIR: ${{ runner.temp }}/adbc-verify
           CI: "false"
           REPOSITORY: ${{ github.repository }}
           # TODO(lidavidm): 3.14 -> 3.15 once conda packages are available
diff --git a/.github/workflows/verify.yml b/.github/workflows/verify.yml
index cbd4ac714f..2c5f022708 100644
--- a/.github/workflows/verify.yml
+++ b/.github/workflows/verify.yml
@@ -134,6 +134,9 @@ jobs:
       - name: Verify
         if: runner.os != 'Windows'
         env:
+          # /tmp is too small on Ubuntu 26.04-based runners
+          # (https://github.com/actions/runner-images/issues/14777)
+          ARROW_TMPDIR: ${{ runner.temp }}/adbc-verify
           CI: "false"
           REPOSITORY: ${{ github.repository }}
           TEST_DEFAULT: "0"
@@ -214,6 +217,8 @@ jobs:
       - name: Verify
         if: matrix.os != 'windows-latest'
         env:
+          # /tmp is too small on Ubuntu 26.04-based runners (https://github.com/actions/runner-images/issues/14777)
+          ARROW_TMPDIR: ${{ runner.temp }}/adbc-verify
           CI: "false"
           REPOSITORY: ${{ github.repository }}
           TEST_DEFAULT: "0"