diff --git a/changelog_unreleased/typescript/18109.md b/changelog_unreleased/typescript/18109.md
new file mode 100644
index 000000000..1029f9034
--- /dev/null
+++ b/changelog_unreleased/typescript/18109.md
@@ -0,0 +1,32 @@
+#### Remove unexpected blank line before union types (#18109 by @jspereiramoura, @fisker)
+
+<!-- prettier-ignore -->
+```tsx
+// Input
+type SuperLongTypeNameLoremIpsumLoremIpsumBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBla =
+  Fooo1000 | Baz2000 | BarLoooooooooooooooooooooooooooooooooooooooooooooooooLong;
+type A = // comment
+  Fooo1000 | Baz2000 | BarLoooooooooooooooooooooooooooooooooooooooooooooooooLong;
+
+// Prettier stable
+type SuperLongTypeNameLoremIpsumLoremIpsumBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBla =
+
+    | Fooo1000
+    | Baz2000
+    | BarLoooooooooooooooooooooooooooooooooooooooooooooooooLong;
+type A = // comment
+
+    | Fooo1000
+    | Baz2000
+    | BarLoooooooooooooooooooooooooooooooooooooooooooooooooLong;
+
+// Prettier main
+type SuperLongTypeNameLoremIpsumLoremIpsumBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBla =
+  | Fooo1000
+  | Baz2000
+  | BarLoooooooooooooooooooooooooooooooooooooooooooooooooLong;
+type A =  // comment
+  | Fooo1000
+  | Baz2000
+  | BarLoooooooooooooooooooooooooooooooooooooooooooooooooLong;
+```
diff --git a/src/language-js/print/assignment.js b/src/language-js/print/assignment.js
index cbe8428a1..534cd44dd 100644
--- a/src/language-js/print/assignment.js
+++ b/src/language-js/print/assignment.js
@@ -142,6 +142,7 @@ function chooseLayout(path, options, print, leftDoc, rightPropertyName) {
     node.type === "ImportAttribute" ||
     (rightNode.type === "CallExpression" &&
       rightNode.callee.name === "require") ||
+    isUnionType(rightNode) ||
     // do not put values on a separate line from the key in json
     options.parser === "json5" ||
     options.parser === "jsonc" ||
diff --git a/tests/format/typescript/union/consistent-with-flow/81-characters.ts b/tests/format/typescript/union/consistent-with-flow/81-characters.ts
new file mode 100644
index 000000000..ae68c1431
--- /dev/null
+++ b/tests/format/typescript/union/consistent-with-flow/81-characters.ts
@@ -0,0 +1,52 @@
+export type ButtonColor =
+  | "primary"
+  | "danger"
+  | "warning"
+  | "muted"
+  | "success";
+export type Button__80 =
+  | "primary"
+  | "danger"
+  | "warning"
+  | "muted"
+  | "success";
+
+export type SupportOptionType =
+  | "int"
+  | "string"
+  | "boolean"
+  | "choice"
+  | "path";
+export type SupportOption_80 =
+  | "int"
+  | "string"
+  | "boolean"
+  | "choice"
+  | "path";
+
+export type RenderContextType =
+    | 'data'
+    | 'header'
+    | 'footer'
+    | 'columnsSelector';
+export type RenderContext_80 =
+    | 'data'
+    | 'header'
+    | 'footer'
+    | 'columnsSelector';
+
+export type PropertyNameNonComputed =
+  | Identifier
+  | NumberLiteral
+  | StringLiteral;
+export type PropertyNameNon_____80 =
+  | Identifier
+  | NumberLiteral
+  | StringLiteral;
+
+type ClassLikeDeclaration =
+  | TSESTree.ClassDeclaration
+  | TSESTree.ClassExpression;
+type ClassLike________80 =
+  | TSESTree.ClassDeclaration
+  | TSESTree.ClassExpression;
diff --git a/tests/format/typescript/union/consistent-with-flow/__snapshots__/format.test.js.snap b/tests/format/typescript/union/consistent-with-flow/__snapshots__/format.test.js.snap
index 343727d11..ce2c2b22e 100644
--- a/tests/format/typescript/union/consistent-with-flow/__snapshots__/format.test.js.snap
+++ b/tests/format/typescript/union/consistent-with-flow/__snapshots__/format.test.js.snap
@@ -1,5 +1,102 @@
 // Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
 
+exports[`81-characters.ts format 1`] = `
+====================================options=====================================
+parsers: ["typescript", "flow"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+export type ButtonColor =
+  | "primary"
+  | "danger"
+  | "warning"
+  | "muted"
+  | "success";
+export type Button__80 =
+  | "primary"
+  | "danger"
+  | "warning"
+  | "muted"
+  | "success";
+
+export type SupportOptionType =
+  | "int"
+  | "string"
+  | "boolean"
+  | "choice"
+  | "path";
+export type SupportOption_80 =
+  | "int"
+  | "string"
+  | "boolean"
+  | "choice"
+  | "path";
+
+export type RenderContextType =
+    | 'data'
+    | 'header'
+    | 'footer'
+    | 'columnsSelector';
+export type RenderContext_80 =
+    | 'data'
+    | 'header'
+    | 'footer'
+    | 'columnsSelector';
+
+export type PropertyNameNonComputed =
+  | Identifier
+  | NumberLiteral
+  | StringLiteral;
+export type PropertyNameNon_____80 =
+  | Identifier
+  | NumberLiteral
+  | StringLiteral;
+
+type ClassLikeDeclaration =
+  | TSESTree.ClassDeclaration
+  | TSESTree.ClassExpression;
+type ClassLike________80 =
+  | TSESTree.ClassDeclaration
+  | TSESTree.ClassExpression;
+
+=====================================output=====================================
+export type ButtonColor =
+  | "primary"
+  | "danger"
+  | "warning"
+  | "muted"
+  | "success";
+export type Button__80 = "primary" | "danger" | "warning" | "muted" | "success";
+
+export type SupportOptionType =
+  | "int"
+  | "string"
+  | "boolean"
+  | "choice"
+  | "path";
+export type SupportOption_80 = "int" | "string" | "boolean" | "choice" | "path";
+
+export type RenderContextType =
+  | "data"
+  | "header"
+  | "footer"
+  | "columnsSelector";
+export type RenderContext_80 = "data" | "header" | "footer" | "columnsSelector";
+
+export type PropertyNameNonComputed =
+  | Identifier
+  | NumberLiteral
+  | StringLiteral;
+export type PropertyNameNon_____80 = Identifier | NumberLiteral | StringLiteral;
+
+type ClassLikeDeclaration =
+  | TSESTree.ClassDeclaration
+  | TSESTree.ClassExpression;
+type ClassLike________80 = TSESTree.ClassDeclaration | TSESTree.ClassExpression;
+
+================================================================================
+`;
+
 exports[`comment.ts format 1`] = `
 ====================================options=====================================
 parsers: ["typescript", "flow"]
@@ -11,9 +108,49 @@ type A1 = /* 4 */ (
   | B
 )[]
 
+type A2 = // dir, exp, arg, modifiers
+  | [string]
+  | [string, ExpressionNode]
+  | [string, ExpressionNode, ExpressionNode]
+  | [string, ExpressionNode, ExpressionNode, ObjectExpression]
+
+type A3 = // dir, exp, arg, modifiers
+  & [string]
+  & [string, ExpressionNode]
+  & [string, ExpressionNode, ExpressionNode]
+  & [string, ExpressionNode, ExpressionNode, ObjectExpression]
+
+type SuperLongTypeNameLoremIpsumLoremIpsumBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBla =
+  Fooo1000 | Baz2000 | BarLoooooooooooooooooooooooooooooooooooooooooooooooooLong;
+
+type SuperLongTypeNameLoremIpsumLoremIpsumBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBl2 =
+  Fooo1000 & Baz2000 & BarLoooooooooooooooooooooooooooooooooooooooooooooooooLong;
+
 =====================================output=====================================
 type A1 = /* 4 */ (A | B)[];
 
+type A2 =  // dir, exp, arg, modifiers
+  | [string]
+  | [string, ExpressionNode]
+  | [string, ExpressionNode, ExpressionNode]
+  | [string, ExpressionNode, ExpressionNode, ObjectExpression];
+
+type A3 = // dir, exp, arg, modifiers
+  [string] &
+    [string, ExpressionNode] &
+    [string, ExpressionNode, ExpressionNode] &
+    [string, ExpressionNode, ExpressionNode, ObjectExpression];
+
+type SuperLongTypeNameLoremIpsumLoremIpsumBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBla =
+  | Fooo1000
+  | Baz2000
+  | BarLoooooooooooooooooooooooooooooooooooooooooooooooooLong;
+
+type SuperLongTypeNameLoremIpsumLoremIpsumBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBl2 =
+  Fooo1000 &
+    Baz2000 &
+    BarLoooooooooooooooooooooooooooooooooooooooooooooooooLong;
+
 ================================================================================
 `;
 
diff --git a/tests/format/typescript/union/consistent-with-flow/comment.ts b/tests/format/typescript/union/consistent-with-flow/comment.ts
index 72ae39339..a30b43b8a 100644
--- a/tests/format/typescript/union/consistent-with-flow/comment.ts
+++ b/tests/format/typescript/union/consistent-with-flow/comment.ts
@@ -2,3 +2,21 @@ type A1 = /* 4 */ (
   | A
   | B
 )[]
+
+type A2 = // dir, exp, arg, modifiers
+  | [string]
+  | [string, ExpressionNode]
+  | [string, ExpressionNode, ExpressionNode]
+  | [string, ExpressionNode, ExpressionNode, ObjectExpression]
+
+type A3 = // dir, exp, arg, modifiers
+  & [string]
+  & [string, ExpressionNode]
+  & [string, ExpressionNode, ExpressionNode]
+  & [string, ExpressionNode, ExpressionNode, ObjectExpression]
+
+type SuperLongTypeNameLoremIpsumLoremIpsumBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBla =
+  Fooo1000 | Baz2000 | BarLoooooooooooooooooooooooooooooooooooooooooooooooooLong;
+
+type SuperLongTypeNameLoremIpsumLoremIpsumBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBlaBl2 =
+  Fooo1000 & Baz2000 & BarLoooooooooooooooooooooooooooooooooooooooooooooooooLong;