The pair met in 2005 but their romance did not become public knowledge until 2006 when Andy romantically ran to her side to kiss her after he won his first senior title.
Andy and Kim at Buckingham Palace when he received his OBE
Rumours have surrounded their engagement for several months after bets on them becoming engaged quickly began to appear. Bookmaker William Hill eventually stopped taking bets on it, with a spokesman saying: "That price was backed heavily. It indicates to us that he got engaged. Maybe someone saw him buying a ring?"
On Wednesday Andy gave no indication to his millions of fans that he was newly engaged, tweeting: 'Off to the Philippines for the first time today, should be a fun trip... Anyone got some suggestions for first time tourists in Manila?"
Andy and Kim often shy away from the spotlight, and Kim has spoken of her desire to not just follow Andy around the world.
Nearly a year ago Andy talked about getting engaged during a Twitter Q&A with fans.
Former professional Darren Cahill asked him: "When are you going to man up and pop the question to that beautiful girlfriend of yours," adding the hashtag: "#Beforeshecomestohersenses".
Andy Murray rushes over to kiss Kim Sears after winning the 2013 Wimbledon Championship
The Scottish ace replied: "Don't start!".
Earlier in 2013 Andy had also revealed that he would love a family with Kim, writing in his autobiography: "I can see myself having a family.
"It is something that I'm starting to think about because Kim and I have been together for eight years."
They were most recently seen together in August when they cuddled together in the stands at a basketball game in New York.