As a performer Lorde knows all too well about pleasing crowds and relished the opportunity to be entertained by a class act, "more energising than a hundred young bands I've seen".
"Never before as an audience member has a band given so much to me," she wrote.
"I went to this show in the pouring rain and heavy wind outdoors at mount smart stadium with my parents, my big green raincoat buttoned up to the chin and pulled tight so no one would see me. My ears ached from the cold, and then Mick [Fleetwood] started banging that kick at the beginning of The Chain, and I forgot how cold it was."
Fleetwood Mac's set spanned more than two-and-a-half hours and every song was a hit.
Lorde went on to describe how each piece of music had a special place in her heart, and her childhood memories.
"I held my parents' hands and screamed the words. The band were completely musically tight - in particular stevie's voice was sharp and clear and full."
She made special mention of infamous front woman Stevie Nicks, and alluded to the group's turbulent past relationships.
"STEVIE. how purely magical it was to see her in front of me, my crescent moon mother, in the flesh, all in black, her hair playing tricks with the light.
"There was so much love coming from the band directed at us but mainly at each other - I can't even tell you how special it was to see Lindsey [Buckingham] kiss Stevie's hand, and speak softly in her ear.
"It made me believe what Lindsey said about the making of Rumours, and where they are now - that it was destiny."
The image she posted was taken during a soaking wet performance of Tusk and features blurred red lights illuminating the stage.
"I guess that's what happens when you try [to] photograph witches and wizards as they weave dreams in front of you," Lorde finished.
The singer returned home from New York last week to attend the Vodafone New Zealand Music Awards on Thursday night.
It's understood she had been busy in the recording studio, laying down tracks for an upcoming album.