The complex is located some 50 km north of Mexico City.
The robot is exploring a tunnel built by Teotihuacan's residents under the Temple of the Feathered Serpent, the third-largest pyramid at Teotihuacan, leading archaeologists to expect an important discovery.
"The technology really helps us archaeologists in doing our work, we use (the robot) as another tool. It has provided very valuable information and helps us plan how to better conduct the research," project director Sergio Gomez told EFE.
This is only the second time a robot has been used at the site and only the third time in history, following the use of a similar apparatus in Egypt to explore one of the Great Pyramids, Gomez said.
The Tlaloc II robot, which was named after the Aztec god of rain and fertility, uses a camera and scanner to provide an exact picture of the condition and shape of the tunnel, Hugo Armando Guerra, one of the engineers who designed the robot, said.
The robot performs a dangerous job, entering areas that may have loose rocks or be subject to collapse, Guerra said.
"These are the types of dangers we avoid by using the robot," Guerra, who also helped create the first-generation robot, said.
The project to explore the 103-meter tunnel under the Temple of the Feathered Serpent started in 2010.