The bank is inviting agencies to pitch for a brief to develop and deliver consumer PR campaigns, targeting consumer and personal finance media, plus social media influencers and customers.
The chosen agency will also work on marketing communications campaigns.
M&S Bank is inviting written responses with pitches due to be held at a later date.
An M&S Bank spokesperson told PRWeek: "We periodically review the agencies on our roster to ensure we're delivering the best possible communications for our customers."
The spokesperson declined to discuss M&S Bank's current PR agency setup.
M&S Bank was launched in 2012, replacing the organisation’s existing financial services arm, M&S Money. The bank is run as a joint venture between Marks & Spencer and HSBC, which owned the now defunct M&S Money.