Celtic manager Brendan Rodgers claimed they had beaten 24 clubs across Europe to sign Chelsea's Musonda, despite failing to sign him last summer.
The 21-year-old, who recently signed a new contract with the English champions until 2022, came through the youth ranks at Anderlecht before moving to Stamford Bridge in 2012.
The 23-year-old former Greuther Furth and FC Augsburg defender spent the first half of last season with the Bundesliga side but a knee injury the player sustained during the Africa Cup of Nations saw his loan spell cut short, but he has now returned until 30 June 2019.
"I was well aware that 67 is a special number here and this is why I took this number and now it's up to me to carry on the legend on the pitch and to enjoy it - hopefully I give the fans what they are looking for", Musonda said. He's really one of the shining lights within the Chelsea academy and has progressed through, had various loans out and has then been a part of their first-team squad.More news: Kenya gov't turns off TV stations airing opposition event
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"It's a great opportunity for him to show his talents". He works very hard and loves his football. "We had permission from Chelsea last season for him to come here and speak to us and he got a feel for it".
Chelsea hope that working under former Blues academy coach Brendan Rodgers will kickstart Musonda's senior career at Celtic, who have developed Virgil van Dijk and Victor Wanyama into Premier League starters in recent years and now have Manchester City starlet Patrick Roberts on loan.
Celtic confirmed the signing of the 12-time Belgium Under-21 global on Monday and Betis sent a Tweet to Celtic following the confirmation of the deal, stating "he always looks good in green and white".
"But I like judging a team in their response". I am very happy to be here. "I am very lucky to be here and I am very happy to be here". "I was close to coming last summer but it didn't happen", he added.