Lego Themed Birthday Cake Ideas

Lego bricks cake

Lego-themed birthday cakes are a great way to start building a birthday party! Whether you go with traditional Lego bricks or make the standard figurine that comes with the sets, your cake design will provide a great addition to a fun theme.

Lego Bricks Cake

A cake made to look like Lego bricks is an excellent way to show off a love of building. Bricks can be made individually and stacked to create the desired effect.


  • 3 two-layer rectangle cakes, filled and crumb coated
  • 2 two-layer square cakes, filled and crumb coated
  • Rolled fondant in bright colors
  • Stacking plates and dowels
  • Pastry bag with coupler
  • Small round decorating tip
  • Royal or buttercream icing, thinned

Brick studs, or the round pieces on top of each Lego that make them stick together, can be made using several methods. Depending on the method you choose from those described below, you will need cupcakes, marshmallows, crispy rice treats, or fondant.

How to Make Brick Studs

If you're going to be stacking several bricks together, wait until assembly time to add the studs to the bricks. Otherwise you may need to remove some in order to get cakes to stack properly. Make your brick studs in one of the following ways:

  • Marshmallows: Cut large marshmallows in your desired thickness. Cover in poured fondant and allow to dry.
  • Cupcakes: Cut the tops off of cupcakes so they are uniform, round sizes. Crumb-coat them and cover with rolled fondant.
  • Crispy rice treats: Use a round cookie cutter and cut the number of studs you need. Cover in fondant, making sure to smooth out the top and sides.
  • Fondant: Roll fondant out so it is very thick. Use a round cookie cutter to cut uniform stud sizes.

Cake Instructions

  1. Cover each of the layer cakes in fondant in your choice of colors.
  2. Place two rectangle cakes parallel to each other horizontally.
  3. Add the third rectangle cake to the left end of the other two cakes, placing it vertically, creating one large rectangular cake.
  4. Use your preferred stacking method to add one square cake to the top of the vertical rectangle cake and the other square cake to the far left of the top rectangle cake.
  5. Use thinned royal icing to adhere the prepared brick studs to the cakes.
  6. Write a birthday message using royal icing or buttercream on the cake studs or on the side of the cake.

Lego Figure Cake

The Lego mini-figure who comes with most building sets makes a great option for a birthday cake design.

Legoman birthday cake


To create the correct shape, you will first need to print a blank outline of the Lego figure. Use the basic figure to make the cake to the left with the free printable from Sweet Benanna & Sam, sized to fit your cake, or work with an image from a coloring book or box.

  • 1 rectangle cake
  • Yellow, blue, and red rolled fondant
  • Black fondant
  • Fondant knife
  • Royal icing, thinned
  • Buttercream icing
  • Cake knife

Cake Instructions

  1. Roll out yellow fondant to approximately 3/4 to one-inch thickness and cut out rectangles for the hands. Curve them around a drinking glass and set aside.
  2. Place the outline on the cake and cut around it to create the basic figure. Do not cut hand shapes.
  3. Carve out a small "dipped" area above the feet on the legs.
  4. Crumb coat the basic figure with buttercream.
  5. Cover the head portion of the cake with yellow rolled fondant rolled to approximately 1/4-inch thickness. Add black fondant eyes and mouth using royal icing as adhesive.
  6. Cover the torso of the figure with blue fondant rolled to approximately 1/4-inch thickness. Use backside of the fondant knife to create indents for the arms.
  7. Cover the legs of the figure with red fondant rolled to approximately 1/4-inch thickness. Use the backside of the fondant knife to make indentations for the legs, feet, and waist as depicted in the photo.
  8. Smooth out areas where the head, torso, and legs meet until you reach the desired effect.
  9. Use the fondant knife to cut out the age of the birthday boy or girl and add it to the shirt using royal icing as adhesive.
  10. Place the yellow hands on the bottom of the arms and secure using some buttercream and royal icing adhesive. The hands may not be totally stiff, so be careful as you move them to the appropriate spot.

More Lego Cake Decorating Ideas

Lego cakes can come in many different shapes, sizes, and styles. Try some of these options for a truly unique cake:

  • Spell out Happy Birthday on top of a cake using fondant or candy Lego bricks.
  • Purchase a Lego decorating kit or edible image and add to the top of the birthday cake.
  • Create a cake using the Lego logo.
  • Use fondant shapes to add a secondary theme to your decorations, like Lego Ninjago or The Lego Movie.
  • Create a 3D cake version of your child's favorite Lego creation.

Build a Great Birthday Cake

Legos provide a good starting point for a birthday cake. Because they can be manipulated to create an assortment of buildings, animals, vehicles, and other things, you can use Legos as a way to build a cake of any shape or size!

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Lego Themed Birthday Cake Ideas