The Croatian rose four spots to 18th, as he and Ukraine's Aleksandr Dolgopolov (up four to 17th) both regained top-20 spots.
Cilic, who has a career high ranking of ninth, backed up his run to the Wimbledon quarter-finals by making the semis at one of his home tournaments in Umag.
He returned to the tour in October, and the 25-year-old was forced to build his ranking back from its lowest point in his lay-off - 47th - to inside the top 20.
Dolgopolov, meanwhile, was a beneficiary of a few players falling spots, as he was not in action last week.
South Africa's Kevin Anderson (down four to 21st), and Spain's Tommy Robredo (down two to 20th) were those to drop - despite Robredo reaching the final in Umag.
Robredo won the event in 2013, hence he dropped rankings points after failing to defend his title, which went the way of Uruguayan qualifier Pablo Cuevas.
Cuevas (up 20 to 40th) and Spain's Pablo Andujar (up 27 to 44th) were too newcomers to the top 50, after breakout weeks.
Andujar claimed the ATP 250 event in Gstaad, with a win over Argentina Juan Monaco in the final.
Monaco climbed back into the top 100 after a return to form, as he moved 24 spots north to 81st.
Other significant risers were Benjamin Becker of Germany (up 10 to 56th), American Jack Sock (up 12 to 60th), and Italy's Simone Bolelli (up 19 to 89th).
Among those to fall heavily were Russia's Mikhail Youzhny (down four to 23rd), Slovakian Martin Klizan (down eight to 58th), Dutchman Robin Haase (down 10 to 61st) and Colombian Alejandro Gonzalez (down 10 to 85th).
In the WTA Tour rankings, there was no change to the top 28 players - with China's Peng Shuai the most significant mover inside the top 50 (up nine to 41st).
Peng claimed the 125K series tournament in Nanchang where she was top seed, dropping just two sets as she cruised to the title.