How far away is the Leo constellation from the earth?

The stars in each constellation are at varying distances from our solar system.

The star Wolf 359, one of the nearest stars to Earth (7.78 light-years), is in Leo.

Gliese 436, a faint star in Leo about 33 light years away.

So to answer your question, the constellation Leo is spread out between 7 to 33 light years away.

Light travels about 6 trillion miles in one year, so between 42 trillion and 198 trillion miles away.