The bombing near the Russian embassy in downtown Kabul also left 24 people wounded, in the latest in a wave of attacks despite an international push to jumpstart Taliban peace talks.
No group has so far claimed responsibility for the bombing, which marks the first major attack on a media organisation in Afghanistan.
Suicide bomber kills four near Russian embassy in Kabul
"Our office bus taking TOLO staff home came under attack," an employee at the channel told AFP, requesting anonymity.
The bombing left some staff members burning inside the vehicle, another employee said, adding that the bus was mostly filled with behind-the-scenes workers from the channel's graphics and dubbing departments.
The loud explosion sent a plume of smoke rising in the sky, with ambulances and fire-fighters rushing to the scene which was littered with charred debris.
The interior ministry said the attack left seven people dead and 24 others wounded.
The Taliban in October declared TOLO and 1TV, both privately run news stations as legitimate "military targets".
The group said the move was in response to their reports claiming that Taliban fighters raped women at a female hostel in Kunduz, after the group briefly captured the northern city in late September last year.
Car bomb explodes near Russian embassy in Kabul, casualties feared
The Taliban rejected the reports as fabrications, saying they were examples of propaganda by the "satanic networks".
The attack, which highlights the growing dangers faced by journalists in Afghanistan, comes just two days after a second round of a four-country meeting in Kabul aimed at reviving talks with the Taliban.
Delegates from Afghanistan, Pakistan, China and the United States convened in the Afghan capital Monday for a one-day meeting seeking a negotiated end to the 14-year Taliban insurgency.
The first round of the so-called "roadmap" talks was held in Islamabad last week as the four nations try to lay the groundwork for direct dialogue between Kabul and the extremist group.
Taliban representatives were notably absent in both rounds and analysts caution that any substantive talks are still a long way off.
The Taliban has stepped up attacks on government and foreign targets in Afghanistan this winter, when fighting usually abates, underscoring a worsening security situation.
Afghan Taliban flex muscles with new telecom 'tax'
Observers say the intensifying insurgency highlights a push by the militants to seize more territory in an attempt to wrangle greater concessions during talks.
Pakistan hosted a milestone first round of talks directly with the Taliban in July.
But the negotiations stalled when the insurgents belatedly confirmed the death of long-time leader Mullah Omar, sparking infighting within the group.
The four-country group is set to hold the next round of discussions on February 6 in Islamabad.
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ