Forward Herrera, 28 and midfielder Pena, 27, have both signed three-year contracts at Ibrox after joining from Pumas and Chivas respectively.
Neither player is in Mexico's squad for the Confederations Cup, but both appeared for the national side as recently as last year.
Herrera previously played under Rangers boss Pedro Caixinha in a loan spell with Santos Laguna, with he and Pena joining Bruno Alves, Ryan Jack, Dalcio, Fabio Cardoso, Daniel Candeias and Alfredo Morelos in making moves to Rangers.
"I am very happy to become part of this great club that has such great supporters," Pena told Rangers TV .
"I have been waiting for this move for many years now. I wanted to become part of European football and I hope I will be able to make my own contribution to the team."
Herrera said: "I know there is a lot of pressure which comes with playing at a big club like this but I have also played with my national team and with big clubs in Mexico so I am prepared for the task.
"I will bring a lot of work and a lot of sacrifice and hopefully a lot of goals!"
Caixinha, who took charge at Ibrox in April, is rebuilding Rangers' squad after the club finished third in last season's Scottish Premiership, a massive 39 points behind Celtic.
Really happy to be here! I want to thank all the fans who have expressed their support and affection.— Eduardo Herrera (@LaloHerrera15) June 22, 2017
All together we'll be stronger! pic.twitter.com/fQuMjv7eYK
"Eduardo fits into the style of play that we want and the style of play that Rangers demands," said the manager. "I am happy to have him on board and I think he is going to be very useful for the team and his characteristics will complement what we are trying to have with this squad.
"I have been following Carlos' career from the end of 2012. He represents everything I want on the pitch in that number eight position and he can give you everything. I believe he can return to the Mexico national squad and Rangers can have a player playing at the next World Cup."