The 27-year-old from Kilmarnock, who trains at the Griphouse gym in Glasgow, will fight in a tournament for the organisation's 115lb title in May.
She was handed the contract with the UFC (Ultimate fighting Championship, the world's premier MMA organisation) after taking her professional record to 8-0 at the weekend with a unanimous decision win over Katja Kankaanpaa at Invicta 7 in Kansas City.
Invicta, the all-women MMA promotion, has had its strawweight division almost entirely swallowed up after the UFC announced plans for its 115lb tournament.
The tournament is to take the form of the UFC's popular reality TV show, The Ultimate Fighter, but with considerably higher stakes than normal thanks to the world title being on the line.
Calderwood said: "The UFC announced a few weeks back it was opening a 115lb women's division, but I couldn't allow myself to think about that as I was preparing for the fight with Katja.
"If I had lost, it would have been back to square one.
"But I was told last night and I had a nervous wait before it was officially announced and I could tell my team, people at the gym and my family."
Calderwood's exploits with Invicta have won her an army of fans in America.
Impressed by her clinical striking in the cage and her softly-spoken demeanour outside the battle arena, fans have universally praised the Scots star known as 'Jojo'.
Her Dinky Ninja Fight Team team-mate Robert Whiteford became Scotland's first ever UFC representative in October when he lost by submission to Jimmy Hettes at UFC Fight Night 30 in Manchester.
Joanne said: "I went down to support Robert and he was carrying my Scotland flag to the cage, the one that I take to the cage with me.
"I just envisioned me doing that in the UFC and I had butterflies in my stomach at the thought of it.
"Now that I'm in the UFC, the hard work will be trying to stay there.
"A lot of people get one chance and don't go back. I need to make sure I arrive there as the best possible fighter I can be."
Invicta's president, Shannon Knapp, allowed Calderwood to leave her contract with a heavy heart, but vowed she would always be welcome.
Joanne added: "Shannon was the one who gave me my chance in America.
"I was emotional when I was discussing the UFC deal with her. She said she knew I was going to be a star from the minute she saw me and said I'd always have a home with Invicta.
"That means a lot to me."