BBC guidelines say presenters should not appear on air using products in which they have any financial interest, and marketing material should not refer to their BBC programmes.
Lightbourne said Norton and Invivo had been open about the partnership.
"Graham Norton's involvement with Invivo wines is a personal project of his and one that he has talked about in his memoirs Life and Loves of a He Devil," Lightbourne said.
"Since 2014, we have produced his hugely popular Graham Norton's Own wine brand."
"We have just released his 2017 vintage in the last week, along with a video in which Graham goes solo this year in his winemaking," he said.
"He has a small shareholding of Invivo."
To date, Norton, who has a 2 per cent stake in Invivo, has donated all proceeds from the wine to charity.
Lightbourne first asked Norton if they could supply his show with wine in 2011, prior to him becoming a shareholder.
"We sent in a case of our sauvignon blanc and they came straight back and said Graham liked our wine ... In 2014, we approached Graham to produce a wine with us which he agreed to, but said we had to make it fun," Lightbourne previously told the Herald.
According to the Mail on Sunday, sales of Graham Norton's Own Sauvignon Blanc have jumped from 14,000 bottles in 2014 to 2 million this year.