Any process that activates or increases the frequency, rate or extent of the phosphorylation of a serine residue of a STAT (Signal Transducer and Activator of Transcription) protein.
synonyms:
upregulation of serine phosphorylation of STAT3 protein,
GO:1903263,
activation of serine phosphorylation of STAT3 protein,
positive regulation of serine phosphorylation of STAT3 protein,
up regulation of serine phosphorylation of STAT3 protein,
up-regulation of serine phosphorylation of STAT3 protein