Objective: To examine the association between pseudo-benign sonographic phenotype and pre-treatment high Ki-67 expression in triple-negative breast cancer (TNBC), and to assess its clinical implications. Methods: We retrospectively enrolled 147 patients with pathologically confirmed invasive TNBC who underwent pre-treatment conventional breast ultrasound at the Affiliated Hospital of North Sichuan Medical College from March 2020 to December 2025. A pre-specified threshold of Ki-67 ≥50% was used to define high expression. The pseudo-benign phenotype was defined as a pathologically confirmed TNBC with an overall benign-like sonographic appearance, mainly considering round or oval shape, circumscribed margins, parallel orientation, posterior enhancement, and absence of calcification. Two experienced sonographers independently reviewed the images while blinded to pathological data; disagreements were resolved by consensus or a third senior sonographer. Logistic regression and ROC analysis were performed. Results: Interobserver agreement was good (κ=0.82, 95%CI: 0.71-0.93). The pseudo-benign phenotype was more frequent in the high Ki-67 group than in the low/intermediate group [38.5% (42/109) vs. 5.3% (2/38), P<0.001]. After adjustment for age, tumor size, histological grade III, T3 stage, and lymphovascular invasion, the phenotype remained independently associated with high Ki-67 expression (OR=11.01, 95%CI: 2.30-52.71, P=0.003). The combined model yielded an AUC of 0.752 (95%CI: 0.666-0.833). Conclusion: Pseudo-benign sonographic phenotype is associated with high Ki-67 expression in pre-treatment core needle biopsy specimens of TNBC. A benign-like appearance should not reduce the need for biopsy and further evaluation when malignancy cannot be clinically excluded.