Nottingham-born Fletcher, 41, began his broadcasting career in the city.
Sports PR firm founder Paul Mace, a lifelong Magpies fan, and property consultancy director Jon Enever have also joined the club.
Chief executive Jason Turner becomes football operations director, with Corrine Rigby as finance director and Amanda Fletcher as commercial director.
Chairman Alan Hardy said: "I am delighted to have put together such a strong team of people who have a diverse and complementary range of football and business skill sets.
"Football is a team game and it is important that we have a committed, enthusiastic and experienced senior group in place dedicated to getting Notts County back to where they belong in the English footballing pyramid."
Enever is a board member of Nottingham Means Business and chairman of Talented Enterprising Nottingham, while Mace wrote the 250,000-word Notts book One Flew Over The Magpies Nest.
Turner arrived at Meadow Lane in April 2016 after previously holding similar positions with Newport County, Plymouth and Cardiff City, while Rigby and Fletcher were both executive appointments by Hardy when he took over the club in January.

Menzies said rectifying "operational issues" at the airport would cost an extra Â£6m in the second half of 2015.
It warned full-year profits could be Â£2m lower than previously forecast.
However, it reported strong profit growth at its US hubs, while its distribution arm was "delivering ahead of forecast".
In a trading update for the 10 months to 30 October, Edinburgh-based Menzies said: "Within the aviation division, service levels at London Gatwick have been restored.
"However, the actions we have put in place to mitigate the operational issues and deliver the customer's operational requirements will cost Â£6m of additional investment, mainly in manpower, in the second half of the year, and will impact this year's earnings.
"Contract negotiations with this customer continue, and we are working towards a resolution before the year end."
Menzies said its aviation division continued to perform well in all regions outside the UK.
Ground handling turns and cargo tonnes were up 9% and 4% respectively, with revenue in the period up 6% on last year.
Chief executive Jeremy Stafford said: "During a busy period of transition, we continue to progress with the group's strategic objectives.
"Our distribution business is quickly gaining traction in the UK e-logistics market, whilst continuing to deliver cost and cash improvement initiatives.
"Aviation continues to benefit from growth in the Americas, whilst we continue to work through UK operational matters.
"I am disappointed that contractual issues at London Gatwick have led us to revise our aviation outlook for this year, albeit largely offset with strong progress in our distribution business.
"The group remains well placed to drive earnings."

The Most Rev Justin Welby told worshippers at Canterbury Cathedral that the attacks risked "causing us to act fearfully, to see a world in which fear triumphs".
But he also said: "On Easter Day hope decisively overcame fear".
Tuesday's bombings in Brussels killed 28 people and injured dozens.
The archbishop said hope can seem far away and fear so close "in the shadow of this week's darkness".
"Fear is reasonable, a normal human reaction," he added.
Pope delivers Easter message of hope
PM praises UK's 'Christian values'
"Easter proclaims to us in flesh and blood that fear and death and terror are not the last words.
"God has spoken life, hope and purpose.
"Terror speaks of a world at war with itself, of faiths at each others' throats.
"Jesus Christ reaches out not in exclusion but in embrace; this is the feast of the victory of God, and we celebrate in the midst of darkness, by our worship and praise shining an unquenchable light."
BBC Radio 5 live presenter Darren Fletcher is one of six appointments to Notts County's new board of directors.
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Logistics group John Menzies has issued a profits warning following problems with its ground handling contract at London Gatwick Airport.
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The Archbishop of Canterbury has warned people not to give in to fear after the attacks in Brussels, in his Easter Sunday sermon.