Ali, the three-times heavy weight boxing champion, passed away after being admitted to hospital in Phoenix Arizona with a respiratory illness.
Fifty-thousand tweets were posted within hours of the news being confirmed in the early hours of Saturday morning. By 08:00 GMT more than 300,000 tweets using the hashtag #MuhammadAli had been posted.
This cartoon image of boxing gloves designed with his famous "float like a butterfly sting like a bee" quote in mind has been shared a number of times from various Twitter accounts.
Ali, who was known as much for his social conscience as his boxing skills, was outspoken and a staunch civil rights activist.  His self belief and showmanship made him an endearing figure across the globe.
@Inkquistive tweeted: "I'm so mean I make medicine sick. #RIPMuhammedAli, your charisma will be missed but celebrated for a lifetime."
@MegaMilkshake23 tweeted: "I am freaking out right now, Muhammad Ali was a hero and true inspiration to so many, I refuse to forget him. #inspire
@carmenblanchard tweeted: "Ali was not afraid to speak his mind, He continuously had his own beliefs and he risked his career to spread a message, Respect. #MuhammedAli
In addition to the hundreds of memes quoting the boxing legend, sports stars, celebrities and public figures have also tweeted their reaction to the news.
A number of images are also being shared including this one of a DC comics cover. @ifeelglorious tweeted the picture with the words "RIP Champ." At the time of writing it had been retweeted over 350 times.
By Rozina Sini
Thousands are posting online tributes to Muhammad Ali who has died at the age of 74.