The star, who played legendary battle-axe Blanche Hunt for over 30 years on the soap, died in December aged 75.
Mourners at the Salford Cathedral service included Bill Roache, who plays her long-suffering son-in-law Ken Barlow, and a tearful Anne Kirkbride, who stars as her daughter, Deirdre.
Several other of the actress's on-screen relatives were also present, including Chris Gascoyne, who plays her grandson Peter Barlow, and young Alex Bain, who stars as her great-grandson.
Leading the tributes, Bill called Maggie a "unique and truly wonderful" actress and "our on-screen, live-in, scene-stealing battle-axe".
Meanwhile, 17-year-old Brooke Vincent, who plays Sophie Webster in the series, offered a particularly special tribute – a poem she had written herself.
"You always made me smile, we always had a joke, We always shared a laugh whilst having a smoke," she recited.
"The one thing I loved was that you were like my Nana, You didn't have a clue who was Hannah Montana.
"The only thing I wanted to say is that you are missed so much, So many people in this building whose hearts you have touched."
Maggie starred in 830 episodes of the series and won several awards for her comical performance.
Illness forced her to pull out of filming last October, with her on-screen absence explained by Blanche going to Portugal to house-sit for a friend.
Viewers are expected to hear of the character's death in May.