Maguire was born to an Irish immigrant family in the poverty-stricken Bank area of Leeds. As a young boy he sang in the choir at St Anne's Church where he was noted for his 'musical voice and poetic tongue'. He received part of his education at Sunday school. Growing up he showed appreciation of his Irish heritage and immersed himself in the music and literature. He was drawn to Romantic poets, such as Shelley and Keats, and began writing his own poetry around this time. After leaving school, he took a job as a photographer's assistant.
The League organised open-air meetings at Vicar's Croft which Maguire and others spoke at, and it was from these that they made contact with building workers whom Maguire helped organise a successful strike in 1889 for a wage increase. This was the backdrop to the Leeds Gasworkers strike in June–July 1890 where Maguire helped organise the workers and other trade unionists to try to stop scabs entering the gasworks, which ultimately led to the strike's victory. After the Socialist League split, Maguire joined the Independent Labour Party and attended its founding conference at Bradford in 1893.
Poetry
Maguire had poetry published in numerous journals including The Commonweal, To Day, Labour Leader, Yorkshire Factory Times, The Leeds Labour Chronicle and Labour Champion. He gathered some of his poems together for the collection Machine Room Chants, which was published posthumously in 1895 and included a foreword written by Keir Hardie.
Death
Maguire died on 8 March 1895 after collapsing of pneumonia earlier in the month. A week later, more than 1000 people turned out for his funeral. He is buried at Beckett Street Cemetery with the epitaph: 'socialist, bold, cautious, true and a loving comrade'. His obituary in the Leeds Mercury read: "He had long given thought to matters affecting capital and labour, and as a public speaker was logical and lucid, holding his own debate... His name as a Labour leader was known all over the North of England, and by his death the Labour movement has lost a keeb sympathiser and an earnest champion." He is commemorated by a in Leeds bus station, a site very close to his principal areas of activity, and in the Tom Maguire Memorial Lecture, a series to be given annually or bi-annually, organised by Richard Burgon, MP for East Leeds, and inaugurated in 2019.