Highly rated Colombian forward James Rodriguez cost the newly promoted Ligue 1 club 45 million euros while midfielder Joao Moutinho heads to France for 25 million euros.
The big-spending Ligue 1 club confirmed the two transfers on Friday in a move which announces the club's presence as a serious player in the European transfer market this summer.
Moutinho, who was linked with a January move to Tottenham, has cost the newly promoted Ligue 1 outfit 25 million euros, while Colombian forward Rodriguez has been sold for an enormous 45 million euros by the Primeira Division champion.
The pair have both signed five-year deals with the principality club, which has also been linked with a 60 million euro move for Atletico Madrid star Radamel Falcao.
Rodriguez is 21 years old but has commanded a huge fee that makes him currently the most expensive deal of the summer, ahead of Mario Gotze who cost Bayern Munich 37 million euros to buy from fellow Champions League finalist Borussia Dortmund.
The deal, in fact, propels the South American attacker into the top 10 most expensive signings of all time, where he now sits ninth just behind compatriot Falcao but ahead of Hernan Crespo in 10th.
Moutinho, 26, is in the prime of his career and will be considered an excellent coup for Claudio Ranieri's men, who will look to storm the top French tier in 2013-14 having won the Ligue 2 title this season.
Monaco was bought in late 2011 by Russian billionaire Dmitry Rybolovlev. The sale has seen the club become a heavyweight in the transfer market this summer with promotion assured.
The lack of tax on income in the principality provides an added lure for players wanting to make as much money as possible during their playing career, compared to the heavy tax rates in mainland France, where Paris Saint-Germain is based.
Both players will be presented to the media when the club regroups after a postseason break.