Ferguson, 29, was the second-highest wicket-taker in the 50-over World Cup in England in 2019 with 21 from nine appearances.
He took 3-50 in the final against England, which the hosts won on boundary countback after the match and a subsequent Super Over were tied.
Yorkshire say that Ferguson will be available for the 14-match group stage “subject to any international involvement”.
The powerful right-armer, who bowls 90mph-plus, could theoretically push for a place in the Kiwis’ Test squad that will tour England in June, although he has made only one Test appearance so far – against Australia at Perth in late 2019.
New Zealand play Test matches at Lord’s (June 2-6) and Edgbaston (June 10-14) before meeting India or Australia in the World Test Championship final at Lord’s (June 18-22).
Yorkshire’s T20 campaign starts on June 10, and they have six fixtures from that date prior to the scheduled end of the WTC final (seven if you count their home game against Worcestershire on June 23, the WTC final reserve day).
Ferguson has a contract with Kolkata Knight Riders in the Indian Premier League, which has an unconfirmed finishing date of June 6.
England have already said that they will allow players to prioritise the latter stages of IPL over the New Zealand series if applicable, and New Zealand have indicated that they will take an identical approach.
Theoretically, a weakened New Zealand could open the door to a Test return for Ferguson, assuming that Kolkata do not themselves reach the latter stages of the IPL.
As ever, the situation is complex and counties are at the whims of external factors, but the bottom line is that Yorkshire have signed a high-class white-ball bowler as they bid to win the 20-over competition for the first time.
Ferguson, who grew up in Auckland, has impressive statistics – 69 wickets in 37 one-day internationals at 25.78 to go with 21 wickets in 11 T20 internationals at 13.23.
He took career-best T20 figures of 5-21 on his home ground of Eden Park in the opening game of the three-match series against West Indies in November, shortly after which he was diagnosed with a stress fracture of the back from which he hopes to return to action later this month.
Commenting on joining Yorkshire, which will be his second county after he played 18 games for Derbyshire in 2018, Ferguson said: “I’m really excited to have signed for Yorkshire.
“I have really fond memories of my time in the county game back in 2018 and look forward to getting back over to the UK.
“It’s a big year for T20 cricket with the T20 World Cup towards the end of the year, so regular top-level T20 cricket throughout the year, particularly at such a big county, is hugely beneficial.”
Ferguson would be unavailable for the Blast knockout stages due to international commitments ahead of that T20 World Cup in India in October/November, and he is one of two overseas players that Yorkshire can field in T20.
He could therefore be paired with South African pace bowlers Duanne Olivier or Mat Pillans, the other two overseas players on Yorkshire’s books.
Martyn Moxon, the Yorkshire director of cricket, said: “Pace bowling is an area where we’ve not been as consistent as we would like in T20, particularly bowling at the death.
“It helps give us that extra security of not being forced to play some of our younger bowlers whose workloads we need to manage.
“They’ve all been injured at various points; none of them have managed to stay fit for a full season yet in their careers.
“What we’re trying to do is make sure that we don’t over-bowl them and that they stay fit for the whole season.
“For example, the eight County Championship games in a row [at the start of the season] will be tough.
“You need that strength in depth, and depth of quality in your seam bowling attack, and Lockie fits the bill. One of his real strengths is bowling at the death, which is a vital part of the game and at times an area where we’ve not done as well as we would have liked.
“He’s a high-quality international white-ball cricketer and I think he’s a great coup for us.
“Obviously we’ve got some important Championship cricket to play first up, but, when T20 comes round, with Lockie in our squad, it’s a really exciting prospect.”
Andrew Gale, the Yorkshire first team coach, agreed. “Lockie has got X-factor pace,” he said. “Pace in T20 cricket is always a good thing, but also his death bowling, in particular, will be hugely beneficial.
“We haven’t had somebody who is reliable and consistent at the death for a number of years.
“This is something that we have been working on with the lads in-house, but also having someone who you can rely on at the death is a big plus.”
Yorkshire are desperate to finally crack T20.
“A lot of work has been put into our white-ball cricket, T20 in particular,” said Moxon. “We’ve invested in the squad to have a real good go at it.”