Gillian Troughton
Gillian Troughton, who will stand for Labour in Copeland.
Both contests are now set to be held in just over a month's time on February 23.
Reed announced before Christmas that he would be leaving Westminster to take up a role at the Sellafield nuclear plant in Copeland, while Hunt declared last week that he'd be stepping down as an MP to become the director of the Victoria & Albert Museum in London.
The pair officially announced their resignations on Friday, meaning the countdown has begun to a significant date for Labour and Jeremy Corbyn.
Both Copeland and Stoke-on-Trent Central will be huge tests of the party's relevance in constituencies that it has controlled for decades, but which now look at risk. Both backed Leave in the June referendum and the party's support in these areas has gradually declined in recent years, amid a growing feeling of disillusion with Westminster.
If Labour loses its grip on just one of these seats it would be a disaster for Jeremy Corbyn. To lose both would likely provoke a renewed conversation about his leadership within the party.
It was initially thought that the Copeland by-election would take place in May in order to coincide with nationwide local elections. However, today's announcement means that the candidates in west Cumbria and Stoke will have little more than four weeks to mobilise their campaigns ahead of voting day.
Labour considered holding the by-elections alongside local elections in May as it would have increased turnout. However, the threat posed by a UKIP campaign fronted by Paul Nuttall in Stoke led party officials to opt for a much earlier date, the Huffington Post reports. This means Labour's opponents will have much less time to prepare.
The Copeland Labour Party chose local councillor and ambulance driver Gillian Troughton to stand in the by-election on Thursday evening. Charity worker Rachel Holliday was dubbed as the favourite by multiple reports but as Business Insider reported earlier this month, Troughton was the leading candidate among local party members.
Corbyn, who will visit Copeland this weekend, regarded Holliday as his preferred choice, Business Insider understands. The charity worker, who voted for the veteran socialist in the most recent leadership contest, was backed by pro-Corbyn group Momentum and was aided by centrist hopefuls like former MP Thomas Docherty being excluded from the final shortlist by a Corbyn-leaning four-person panel from the party's National Executive Committee (NEC).
Reacting to Troughton's selection, the Labour leader said: "Gillian is a local councillor with a strong track record of getting things done for her community. She has campaigned tirelessly to maintain local hospital services." Shadow business secretary Clive Lewis will also visit the area in the coming weeks.
Fiona Mills will stand for UKIP in the west Cumbrian constituency, while the local Conservative Party is yet to select its candidate. Likely runners are Stephen Haraldsen, who Reed defeated in 2015, and Chris Whiteside.
UKIP is also set to announce its Stoke candidate on Saturday, with leader Nuttall reported to be eyeing up a run in a seat that the party finished second behind Labour at the last election. Failure to wrestle the seat from Labour's grasp would be a disappointment for the pro-Brexit party with clear opportunities to grow its presence in the Commons being few and far between.
Labour and the Tories will announce their candidates for Stoke next week. The former will produce a shortlist on Tuesday before selecting a candidate on Wednesday.