This year, the sextet's success has landed them on stage at the Marina Bay Floating Platform where they will perform at the NDP for the first time.
"We are very honoured to be participating in this year's NDP," 32-year-old tenor Juni Goh in Mandarin said on Tuesday (July 24).
"We've always been envious of those who had performed at the parade. We had to say yes to this rare opportunity to perform in front of so many Singaporeans on such a prestigious platform."
Soprano Tay Kexin pointed to the success of their video last year that landed them onto the NDP organising committee's radar.
Till date, last year's video, which comprises a medley of 23 songs including Singapore Town, Count On Me Singapore and We Are Singapore, has drawn more than 250,000 YouTube views. It was also shared by PM Lee.
Ms Tay, 30, said: "Last year's version was not our first attempt at making a medley of NDP songs but it was the most successful."
MICappella - who sing without instrumentation as their name suggests - performed National Day song medleys in 2013 and 2015 and posted the videos online.
For this year's medley, the band has included three more songs - Di Tanjong Katong, Munnaeru Vaalibaa and Singai Naadu.
To get the Tamil words right, alto Calin Wong, 32, had a friend who speaks the language to read out the lyrics and record it for everyone to learn.
Band leader and vocal percussionist Peter Huang, 36, said: "I hope our Tamil-speaking friends can accept our pronunciation."
The band spent more than 10 hours shooting this year's video titled Evolution of NDP Songs V2.0. So far, it has attracted more than 20,000 views on YouTube.
MICappella also roped in some primary school children to play younger versions of themselves. Mr Goh said: "We wanted this year's video to show how we have grown up listening to the NDP songs."
Formed in 2009, MICappella - which includes two other members bass Goh Mingwei, 31, and baritone Eugene Yip, 36 - emerged as runners-up on popular TV singing competition The Sing-Off China in 2012.
In 2015, they became the first Singaporean group to perform at the London A Cappella Festival. The group was also awarded the 'best Asian a cappella album' prize at the 2017 Contemporary A Cappella Recording Awards in the United States.
Mr Juni Goh said that rehearsing on the large NDP stage led to some initial confusion as to where each member was supposed to stand but those teething days are now over. "We spent some time getting used to the floating platform," he said. "At this moment, we are ready to give a great performance."