The newsreader, 64, was diagnosed with stage-four bowel cancer in April 2014 and is currently undergoing chemotherapy.
In a tweet, he said: ‘Absolutely gutted. After talking to colleagues and doctors I’ve decided to stay away from the newsroom.
‘I’m on a few weeks cancer treatment break at the moment but, on a balance of risks, we all decided I must heed the advice for those with underlying health issues.’
Mr Alagiah underwent 17 rounds of chemotherapy to treat advanced bowel cancer in 2014 before returning to presenting duties in 2015.
In January 2018, he revealed that the cancer had returned.
George Alagiah, 64, has revealed he will be staying away from the BBC newsroom because of the coronavirus
He has decided to self-isolate because of the risk the coronavirus poses to people with underlying health issues
It comes as 407 more people tested positive for the virus in the UK, with the total number now standing at 1,543.
The Government has advised people classed as ‘vulnerable’ to ensure they are ‘largely shielded from social contact’ for around 12 weeks, or possibly longer.
This includes people over the age of 70, pregnant women and people with certain health conditions or undergoing treatment such as chemotherapy.
Mr Alagiah’s agent Mary Greenham, from Newspresenters, had said on Monday night that he would not be working from the newsroom after consulting with his doctors and editor.
He is self-isolating, Ms Greenham confirmed.
Alagiah said: ‘It’s been a difficult decision. At a time like this I so wanted to play my part in the BBC newsroom, working with my colleagues to report on this unprecedented crisis – especially as so many are turning to the BBC to make sense of what can seem a frightening and confusing situation.
‘After talking to my doctors and my editor we all decided that, on a balance of risks, it was probably best that I withdraw from the newsroom.’
Good Morning Britain host Susanna Reid, who is self-isolating after one of her children developed a ‘persistent cough’, was among the people sending well wishes to Alagiah.
She tweeted: ‘Huge best wishes George x’.
BBC Breakfast presenters Naga Munchetty and Louise Minchin also tweeted messages of support.
Munchetty tweeted: ‘Stay safe George x’, while Minchin wrote: ‘Take care’.