diff --git a/.changeset/brave-tips-protect.md b/.changeset/brave-tips-protect.md
new file mode 100644
index 00000000000..4998bf9b3aa
--- /dev/null
+++ b/.changeset/brave-tips-protect.md
@@ -0,0 +1,5 @@
+---
+"@smithy/shared-ini-file-loader": patch
+---
+
+Treat absence of prefix whitespace as section keys when reading ini files
diff --git a/packages/shared-ini-file-loader/src/parseIni.spec.ts b/packages/shared-ini-file-loader/src/parseIni.spec.ts
index db21290cc93..273044af7d0 100644
--- a/packages/shared-ini-file-loader/src/parseIni.spec.ts
+++ b/packages/shared-ini-file-loader/src/parseIni.spec.ts
@@ -90,34 +90,63 @@ describe(parseIni.name, () => {
       });
     });
 
-    it("returns data from main section, and not subsection", () => {
-      const mockProfileDataWithSubSettings = {
-        key: "value",
-        subSection: { subKey: "subValue" },
-      };
-      const mockInput = getMockProfileContent(mockProfileName, mockProfileDataWithSubSettings);
-      expect(parseIni(mockInput)).toStrictEqual({
-        [mockProfileName]: {
-          key: "value",
-          [["subSection", "subKey"].join(CONFIG_PREFIX_SEPARATOR)]: "subValue",
-        },
+    describe("returns data from main section, and not subsection", () => {
+      it("if subsection comes after section", () => {
+        const mockProfileDataWithSubSettings = {
+          key: "keyValue",
+          subSection: {
+            key: "keyValueInSubSection",
+            subKey: "subKeyValue",
+          },
+        };
+        const mockInput = getMockProfileContent(mockProfileName, mockProfileDataWithSubSettings);
+        expect(parseIni(mockInput)).toStrictEqual({
+          [mockProfileName]: {
+            key: "keyValue",
+            [["subSection", "key"].join(CONFIG_PREFIX_SEPARATOR)]: "keyValueInSubSection",
+            [["subSection", "subKey"].join(CONFIG_PREFIX_SEPARATOR)]: "subKeyValue",
+          },
+        });
+
+        const mockProfileName2 = "mock_profile_name_2";
+        const mockProfileDataWithSubSettings2 = {
+          key: "keyValue2",
+          subSection: {
+            key: "keyValue2InSubSection",
+            subKey: "subKeyValue2",
+          },
+        };
+        const mockInput2 = getMockProfileContent(mockProfileName2, mockProfileDataWithSubSettings2);
+        expect(parseIni(`${mockInput}${mockInput2}`)).toStrictEqual({
+          [mockProfileName]: {
+            key: "keyValue",
+            [["subSection", "key"].join(CONFIG_PREFIX_SEPARATOR)]: "keyValueInSubSection",
+            [["subSection", "subKey"].join(CONFIG_PREFIX_SEPARATOR)]: "subKeyValue",
+          },
+          [mockProfileName2]: {
+            key: "keyValue2",
+            [["subSection", "key"].join(CONFIG_PREFIX_SEPARATOR)]: "keyValue2InSubSection",
+            [["subSection", "subKey"].join(CONFIG_PREFIX_SEPARATOR)]: "subKeyValue2",
+          },
+        });
       });
 
-      const mockProfileName2 = "mock_profile_name_2";
-      const mockProfileDataWithSubSettings2 = {
-        key: "value2",
-        subSection: { subKey: "subValue2" },
-      };
-      const mockInput2 = getMockProfileContent(mockProfileName2, mockProfileDataWithSubSettings2);
-      expect(parseIni(`${mockInput}${mockInput2}`)).toStrictEqual({
-        [mockProfileName]: {
-          key: "value",
-          [["subSection", "subKey"].join(CONFIG_PREFIX_SEPARATOR)]: "subValue",
-        },
-        [mockProfileName2]: {
-          key: "value2",
-          [["subSection", "subKey"].join(CONFIG_PREFIX_SEPARATOR)]: "subValue2",
-        },
+      it("if subsection comes before section", () => {
+        const mockProfileDataWithSubSettings = {
+          subSection: {
+            key: "keyValueInSubSection",
+            subKey: "subKeyValue",
+          },
+          key: "keyValue",
+        };
+        const mockInput = getMockProfileContent(mockProfileName, mockProfileDataWithSubSettings);
+        expect(parseIni(mockInput)).toStrictEqual({
+          [mockProfileName]: {
+            [["subSection", "key"].join(CONFIG_PREFIX_SEPARATOR)]: "keyValueInSubSection",
+            [["subSection", "subKey"].join(CONFIG_PREFIX_SEPARATOR)]: "subKeyValue",
+            key: "keyValue",
+          },
+        });
       });
     });
   });
diff --git a/packages/shared-ini-file-loader/src/parseIni.ts b/packages/shared-ini-file-loader/src/parseIni.ts
index 1e5fa8c1a53..1a63a31c052 100644
--- a/packages/shared-ini-file-loader/src/parseIni.ts
+++ b/packages/shared-ini-file-loader/src/parseIni.ts
@@ -11,15 +11,15 @@ export const parseIni = (iniData: string): ParsedIniData => {
   let currentSection: string | undefined;
   let currentSubSection: string | undefined;
 
-  for (let line of iniData.split(/\r?\n/)) {
-    line = line.split(/(^|\s)[;#]/)[0].trim(); // remove comments and trim
-    const isSection: boolean = line[0] === "[" && line[line.length - 1] === "]";
+  for (const iniLine of iniData.split(/\r?\n/)) {
+    const trimmedLine = iniLine.split(/(^|\s)[;#]/)[0].trim(); // remove comments and trim
+    const isSection: boolean = trimmedLine[0] === "[" && trimmedLine[trimmedLine.length - 1] === "]";
     if (isSection) {
       // New section found. Reset currentSection and currentSubSection.
       currentSection = undefined;
       currentSubSection = undefined;
 
-      const sectionName = line.substring(1, line.length - 1);
+      const sectionName = trimmedLine.substring(1, trimmedLine.length - 1);
       const matches = prefixKeyRegex.exec(sectionName);
       if (matches) {
         const [, prefix, , name] = matches;
@@ -36,15 +36,19 @@ export const parseIni = (iniData: string): ParsedIniData => {
         throw new Error(`Found invalid profile name "${sectionName}"`);
       }
     } else if (currentSection) {
-      const indexOfEqualsSign = line.indexOf("=");
+      const indexOfEqualsSign = trimmedLine.indexOf("=");
       if (![0, -1].includes(indexOfEqualsSign)) {
         const [name, value]: [string, string] = [
-          line.substring(0, indexOfEqualsSign).trim(),
-          line.substring(indexOfEqualsSign + 1).trim(),
+          trimmedLine.substring(0, indexOfEqualsSign).trim(),
+          trimmedLine.substring(indexOfEqualsSign + 1).trim(),
         ];
         if (value === "") {
           currentSubSection = name;
         } else {
+          if (currentSubSection && iniLine.trimStart() === iniLine) {
+            // Reset currentSubSection if there is no whitespace
+            currentSubSection = undefined;
+          }
           map[currentSection] = map[currentSection] || {};
           const key = currentSubSection ? [currentSubSection, name].join(CONFIG_PREFIX_SEPARATOR) : name;
           map[currentSection][key] = value;