Singer-songwriter James, 35, will perform Embers in Rotterdam on Saturday as he bids to secure victory for the UK.
He is the older brother of John, 30, whose hit songs include Love Me Again.
James revealed his sibling, who has performed around the world with the likes of Calvin Harris, told him to enjoy the big day.
Speaking during a welcome reception hosted by Joanna Roper, the UK’s ambassador to the Netherlands, James said: “Obviously we speak all the time, he’s like, ‘you’ve just got to enjoy every minute of it’.
“He’s done so many massive things, not as big as this, because this is huge, he’s never sang to 180 million people. He’s sang to thousands and thousands of people and been on huge TV shows and stuff so he knows what it’s like.
“He was like, ‘it’s an amazing experience, you’ve just got to take every moment in and not let it pass you by because being up there and being on that stage is a gift and is beautiful’. He knows what it’s like so it’s great to have him as a confidant.”
James, from Settle, North Yorkshire has previously worked with acts including Rudimental and Ed Sheeran.
He was originally set to be the UK’s Eurovision entry last year before the event was cancelled due to the pandemic.
For the 2021 competition James has replaced ballad My Last Breath with the bouncier Embers.
He said the track was designed to deliver a hopeful message following a traumatic year.
He said: “Embers is the idea of coming back out, it can be reignited, it hasn’t died out yet. And it was the idea of people being apart but the love was still there and it can still be reignited when you see each other again.
“That was the idea for me. And obviously we’ve been through such a rubbish time all together and I wanted to sing something on stage that was fun and exciting and upbeat and that we could have a dance to and have a party and set some fireworks off to.”
The Eurovision Song Contest Grand Final is on May 22 at 8pm on BBC One.